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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang=en>
<head><meta content="text/html;charset=utf-8" http-equiv=Content-Type>
<title>CSS Fonts Module Level 3</title>
<!--
FIXME when publishing: copy the current default.css and link to
"default.css" rather than "../default.css"
-->
<link href="default.css" rel=stylesheet type="text/css">
<style type="text/css">
body {
padding: 2em 70px 2em 70px;
}
p + p, p.mtb {
margin-top: 0.8em;
text-indent: 0px;
}
#fontformats td, #fontformats th {
padding-right: 2em;
text-align: left;
}
dd {
margin-bottom: 1em;
}
pre {
font-size: 100%;
}
#authors dd {
margin-bottom: 0;
}
#fontstylematchingalg {
list-style-type: lower-alpha;
}
#fontmatchingalg ul, #fontmatchingalg ol {
margin-top: 0.8em;
}
#fontmatchingalg li + li {
margin-top: 0.8em;
}
div.example {
padding: 1em;
margin-top: 1em;
}
div.example + div.example {
margin-top: 2em;
}
div.figure {
page-break-inside: avoid;
}
.data {
margin: 1em auto;
border-collapse: collapse;
}
.data caption {
width: 100%;
text-align: center;
}
.data td, .data th {
padding-left: 0.5em;
padding-right: 0.5em;
text-align: center;
}
.data thead th:first-child {
text-align: right;
}
.data tbody th:first-child {
text-align: left;
padding-left: 0.5em;
}
pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
div.featex {
width: 700px;
}
div.featex img {
margin: auto;
display: block;
}
</style>
<link href="http://www.w3.org/StyleSheets/TR/W3C-WD.css" rel=stylesheet
type="text/css">
<body>
<div class=head> <!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1>CSS Fonts Module Level 3</h1>
<h2 class="no-num no-toc" id=w3c-working>W3C Working Draft 4 October 2011</h2>
<dl id=authors>
<dt>This version:</dt>
<!-- <dd><a href="http://dev.w3.org/csswg/css3-fonts/">http://dev.w3.org/csswg/css3-fonts/</a> -->
<dd><a
href="http://www.w3.org/TR/2011/WD-css3-fonts-20111004/">http://www.w3.org/TR/2011/WD-css3-fonts-20111004/</a>
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css3-fonts/">http://www.w3.org/TR/css3-fonts/</a>
<dt>Latest editor's draft:
<dd><a
href="http://dev.w3.org/csswg/css3-fonts/">http://dev.w3.org/csswg/css3-fonts/</a>
<dt>Previous version (CSS3 Fonts):
<dd><a
href="http://www.w3.org/TR/2011/WD-css3-fonts-20110324/">http://www.w3.org/TR/2011/WD-css3-fonts-20110324/</a>
<dd><a
href="http://www.w3.org/TR/2009/WD-css3-fonts-20090618/">http://www.w3.org/TR/2009/WD-css3-fonts-20090618/</a>
<dd><a
href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">http://www.w3.org/TR/2002/WD-css3-fonts-20020802/</a>
<dt>Previous version (CSS3 Web Fonts):
<dd><a
href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/</a>
<dt>Editor:
<dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2011 <a href="http://www.w3.org/"><acronym
title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute
of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym
title="European Research Consortium for Informatics and
Mathematics">ERCIM</acronym></a>, <a
href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a
href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p>This CSS3 module describes how font properties are specified and how
font resources are loaded dynamically. The contents of this specification
are a consolidation of content previously divided into <a
href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
Web Fonts</a> modules.
<h2 class="no-num no-toc" id=status>Status of this document</h2>
<!--begin-status-->
<p><em>This section describes the status of this document at the time of
its publication. Other documents may supersede this document. A list of
current W3C publications and the latest revision of this technical report
can be found in the <a href="http://www.w3.org/TR/">W3C technical reports
index at http://www.w3.org/TR/.</a></em>
<p>Publication as a Working Draft does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or
obsoleted by other documents at any time. It is inappropriate to cite this
document as other than work in progress.
<p>The (<a
href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a href="mailto:www-style@w3.org">www-style@w3.org</a> (see
<a href="http://www.w3.org/Mail/Request">instructions</a>) is preferred
for discussion of this specification. When sending e-mail, please put the
text “css3-fonts” in the subject, preferably like this:
“[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
<p>This document was produced by the <a
href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
the <a href="http://www.w3.org/Style/">Style Activity</a>).
<p>This document was produced by a group operating under the <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
2004 W3C Patent Policy</a>. W3C maintains a <a
href="http://www.w3.org/2004/01/pp-impl/32061/status"
rel=disclosure>public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
6 of the W3C Patent Policy</a>.</p>
<!--end-status-->
<h3 class="no-num no-toc" id=atrisk>Features at risk</h3>
<p>The following features are at risk and may be removed when exiting CR:
<ul>
<li>Description of the same origin restriction for fonts, if replaced by
similar mechanism.
</ul>
<h2 class="no-num no-toc" id=contents>Table of Contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
<li><a href="#typography-background"><span class=secno>2 </span>Typography
Background</a>
<li><a href="#basic-font-props"><span class=secno>3 </span>Basic font
properties</a>
<ul class=toc>
<li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
family: the font-family property</a>
<ul class=toc>
<li><a href="#generic-font-families"><span class=secno>3.1.1
</span>Generic font families</a>
</ul>
<li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
weight: the font-weight property</a>
<li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
width: the font-stretch property</a>
<li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
the font-style property</a>
<li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
the font-size property</a>
<li><a href="#font-size-adjust-prop"><span class=secno>3.6
</span>Relative sizing: the font-size-adjust property</a>
<li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
property: the font property</a>
<li><a href="#font-synthesis-prop"><span class=secno>3.8
</span>Controlling synthetic faces: the font-synthesis property</a>
</ul>
<li><a href="#font-resources"><span class=secno>4 </span>Font
resources</a>
<ul class=toc>
<li><a href="#font-face-rule"><span class=secno>4.1 </span>The
@font-face rule</a>
<li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
family: the font-family descriptor</a>
<li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
src descriptor</a>
<li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
descriptors: the font-style, font-weight, font-stretch descriptors</a>
<li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
range: the unicode-range descriptor</a>
<li><a href="#font-rend-desc"><span class=secno>4.6 </span>Font
features: the font-variant and font-feature-settings descriptors</a>
<li><a href="#font-face-loading"><span class=secno>4.7 </span>Font
loading guidelines</a>
<li><a href="#same-origin-restriction"><span class=secno>4.8
</span>Same-origin restriction for fonts</a>
<ul class=toc>
<li><a href="#default-same-origin-restriction"><span class=secno>4.8.1
</span>Default same-origin restriction</a>
<li><a href="#allowing-cross-origin-font-loading"><span
class=secno>4.8.2 </span>Allowing cross-origin font loading</a>
</ul>
</ul>
<li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
matching algorithm</a>
<ul class=toc>
<li><a href="#font-style-matching"><span class=secno>5.1 </span>Matching
font styles</a>
<li><a href="#char-handling-issues"><span class=secno>5.2
</span>Character handling issues</a>
<li><a href="#font-matching-changes"><span class=secno>5.3 </span>Font
matching changes since CSS 2.1</a>
</ul>
<li><a href="#font-rend-props"><span class=secno>6 </span>Font feature
properties</a>
<ul class=toc>
<li><a href="#glyph-selection-positioning"><span class=secno>6.1
</span>Glyph selection and positioning</a>
<li><a href="#language-specific-support"><span class=secno>6.2
</span>Language-specific display</a>
<li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
the font-kerning property</a>
<li><a href="#font-variant-position-prop"><span class=secno>6.4
</span>Subscript, superscript and ordinal forms: the
font-variant-position property</a>
<li><a href="#font-variant-ligatures-prop"><span class=secno>6.5
</span>Ligatures: the font-variant-ligatures property</a>
<li><a href="#font-variant-caps-prop"><span class=secno>6.6
</span>Capitalization: the font-variant-caps property</a>
<li><a href="#font-variant-numeric-prop"><span class=secno>6.7
</span>Numerical formatting: the font-variant-numeric property</a>
<li><a href="#font-variant-alternates-prop"><span class=secno>6.8
</span>Alternates and swashes: the font-variant-alternates property</a>
<li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
font specific alternates: the @font-feature-values rule</a>
<li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
</span>East Asian text rendering: the font-variant-east-asian
property</a>
<li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
shorthand for font rendering: the font-variant property</a>
<li><a href="#font-feature-settings-prop"><span class=secno>6.12
</span>Low-level font feature settings control: the
font-feature-settings property</a>
<li><a href="#font-language-override-prop"><span class=secno>6.13
</span>Font language override: the font-language-override property</a>
</ul>
<li><a href="#rendering-considerations"><span class=secno>7
</span>Resolving font feature settings </a>
<li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
platform font properties to CSS properties</a>
<li class=no-num><a href="#font-licensing">Appendix B: Font licensing
issues</a>
<li class=no-num><a href="#font-feature-values-DOM">Appendix C: DOM
Interfaces</a>
<li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
<ul class=toc>
<li class=no-num><a href="#recent-changes"> Changes from the March 2011
CSS3 Fonts Working Draft</a>
</ul>
<li class=no-num><a href="#acknowledgments">Acknowledgments</a>
<li class=no-num><a href="#references">References</a>
<ul class=toc>
<li class=no-num><a href="#normative-references">Normative
References</a>
<li class=no-num><a href="#other-references">Other References</a>
</ul>
<li class=no-num><a href="#index">Index</a>
<li class=no-num><a href="#property-index">Property index</a>
</ul>
<!--end-toc-->
<h2 id=introduction><span class=secno>1 </span>Introduction</h2>
<p>A font provides a resource containing the visual representation of
characters. At the simplest level it contains information that maps
character codes to shapes (called glyphs) that represent these characters.
Fonts sharing a common design style are commonly grouped into font
families classified by a set of standard font properties. Within a family,
the shape displayed for a given character can vary by stroke weight, slant
or relative width, among others. A given font face is described by a
unique combination of these properties. For a given range of text, CSS
font properties are used to select a font family and a specific font face
within that family to be used when rendering that text. As a simple
example, to use the bold form of Helvetica one could use:
<pre>body {
font-family: Helvetica;
font-weight: bold;
}</pre>
<p>Font resources may be local, installed on the system on which a user
agent is running, or downloadable. For local font resources descriptive
information can be obtained directly from the font resource. For
downloadable font resources (sometimes referred to as web fonts), the
descriptive information is included with the reference to the font
resource.
<p>Families of fonts typically don't contain a single face for each
possible variation of font properties. The CSS font selection mechanism
describes how to match a given set of CSS font properties to a given font
face.
<h2 id=typography-background><span class=secno>2 </span>Typography
Background</h2>
<!--
- Wide variation in character forms, glyphs
- Use of diacritics adds complications to even "simple" alphabets
- Examples from Czech, Slovak, African romanizations
- Vietnamese stacking example
- General use of ligatures
- Required for languages such as Arabic
- Problems with creating "universal fonts"
-->
<p><em>This section is included as background for some of the problems and
situations that are described in other sections. It should be viewed as
informative only.</em>
<p> Typographic traditions vary across the globe so there is no unique way
to classify all fonts across languages and cultures. For even common Latin
letters, wide variations are possible:
<div class=figure><img alt="variations in glyphs for a single character"
src=aaaaaa.png>
<p class=caption>One character, many glyph variations
</div>
<p>Differences in the anatomy of letterforms is one way to distinguish
fonts. For Latin fonts, flourishes at the ends of a character's main
strokes, or serifs, can distinguish a font from those without. Similar
comparisons exist in non-Latin fonts between fonts with tapered strokes
and those using primarily uniform strokes:
<div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
<p class=caption>Letterforms with and without serifs
</div>
<div class=figure><img alt="serif vs. non-serifs for japanese"
src=minchovsgothic.png>
<p class=caption>Similar groupings for Japanese typefaces
</div>
<p>Fonts contain letterforms and the data needed to map characters to these
letterforms. Often this may be a simple one-to-one mapping but more
complex mappings are also possible. The use of combining diacritic marks
creates many variations for an underlying letterform:
<div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
<p class=caption>Variations with diacritic marks
</div>
<!-- Include stacking diacritics? Hmm, Vietnamese example? -->
<p>A sequence of characters can be represented by a single glyph known as a
ligature:
<div class=figure><img alt="example of a fi ligature"
src=final-ligature.png>
<p class=caption>Ligature example
</div>
<p>Visual transformations based on textual context like this may be a
stylistic option for European languages but are required to correctly
render languages like Arabic; the lam and alef characters below
<em>must</em> be combined when they exist in sequence:
<div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
<p class=caption>Required Arabic ligature
</div>
<p>The relative complexity of these shaping transformations requires
additional data within the font.
<p>Sets of font faces with various stylistic variations are often grouped
together into font families. In the simplest case a regular face is
supplemented with bold and italic faces but much more extensive groupings
are possible. Variations in the thickness of letterform strokes, or the
weight, or the overall proportions of the letterform, or the width, are
most common. In the example below, each letter uses a different font face
within the Univers font family. The width used increases from top to
bottom and the weight increases from left to right:
<div class=figure><img alt="various width and weight variations within a
single family" src=weightwidthvariations.png>
<p class=caption>Weight and width variations within a single font family
</div>
<p>Creating fonts that support multiple scripts is a difficult task;
designers need to understand the cultural traditions surrounding the use
of type in different scripts and come up with letterforms that somehow
share a common theme. Many languages often share a common script and each
of these languages may have noticeable stylistic differences. The Arabic
script is shared by Persian and Urdu and Cyrillic is used with many
languages, not just Russian.
<p>The character map of a font defines the mapping of characters to glyphs
for that font. If a document contains characters not supported by the
character maps of explicitly specified fonts, a user agent may use a
system font fallback procedure to locate an appropriate font that does. If
no appropriate font can be found, some form of "missing glyph" character
will be rendered by the user agent. Fallback can occur because fonts are
not explicitly specified or because authors fail to explicitly indicate
the encoding used by a document.
<p>Although the character map of a font maps a given character to a glyph
for that character, modern font technologies such as OpenType and AAT
(Apple Advanced Typography) provide a richer set of rules for performing
this mapping. Fonts in these forms allow these features to be embedded in
the font itself and controlled by applications. Common typographic
features which can be specified this way include ligatures, swashes,
contextual alternates, proportional and tabular figures, and automatic
fractions, to list just a few. For a visual overview of OpenType features,
see the <a href="#OPENTYPE-FONT-GUIDE"
rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.</p>
<!-- illustration of various font features -->
<!-- common ligs, uncommon ligs, old-style figures, lining figures, prop/tabular figures,
automatic fractions, proportional/full-width Japanese, glyph variations over time,
stylistic alternates, swashes, small-caps -->
<h2 id=basic-font-props><span class=secno>3 </span>Basic font properties</h2>
<p>The particular font face used to render a character is determined by the
font family and other font properties that apply to a given element. This
structure allows settings to be varied independent of each other.</p>
<!-- prop: font-family -->
<h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
href="#propdef-font-family">font-family</a> property</h3>
<table class=propdef id=namefont-family>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-family>font-family</dfn>
<tr>
<td>Value:
<td>[[ <family-name> | <generic-family> ] [, <family-name> |
<generic-family>]* ] | inherit
<tr>
<td>Initial:
<td>depends on user agent
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>This property specifies a prioritized list of font family names or
generic family names. Unlike other CSS properties, component values are a
comma-separated list indicating alternatives. A user agent iterates
through the list of family names until it matches an available font that
contains a glyph for the character to be rendered. This allows for
differences in available fonts across platforms and for differences in the
range of characters supported by individual fonts.
<p>A font family name only specifies a name given to a set of font faces,
it does not specify an individual face. Given the availability of the
fonts below, Futura would match but Futura Medium would not:
<div class=figure><img alt="family and face names"
src=familyvsfacename.png>
<p class=caption>Family and individual face names
</div>
<p>Consider the example below:
<div class=example>
<pre>body {
font-family: Helvetica, Verdana, sans-serif;
}</pre>
<p>If Helvetica is available it will be used when rendering. If neither
Helvetica nor Verdana is present, then the user-agent-defined sans serif
font will be used.</p>
</div>
<p>There are two types of font family names:
<dl>
<dt><family-name>
<dd>The name of a font family of choice such as Helvetica or Verdana in
the previous example.
<dt><generic-family>
<dd> The following generic family keywords are defined: ‘<code
class=property><a href="#serif">serif</a></code>’, ‘<code
class=property><a href="#sans-serif">sans-serif</a></code>’, ‘<code
class=property><a href="#cursive">cursive</a></code>’, ‘<code
class=property><a href="#fantasy">fantasy</a></code>’, and ‘<code
class=property><a href="#monospace">monospace</a></code>’. These
keywords can be used as a general fallback mechanism when an author's
desired font choices are not available. As keywords, they must not be
quoted. Authors are encouraged to append a generic font family as a last
alternative for improved robustness.
</dl>
<p>Font family names must either be given quoted as <a
href="//www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or unquoted
as a sequence of one or more <a
href="//www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
This means most punctuation characters and digits at the start of each
token must be escaped in unquoted font family names.
<p>For example, the following declarations are invalid:
<pre>
font-family: Red/Black, sans-serif;
font-family: "Lucida" Grande, sans-serif;
font-family: Ahem!, sans-serif;
font-family: test@foo, sans-serif;
font-family: #POUND, sans-serif;
font-family: Hawaii 5-0, sans-serif;
</pre>
<p>If a sequence of identifiers is given as a font family name, the
computed value is the name converted to a string by joining all the
identifiers in the sequence by single spaces.
<p>To avoid mistakes in escaping, it is recommended to quote font family
names that contain white space, digits, or punctuation characters other
than hyphens:
<pre>
body { font-family: "New Century Schoolbook", serif }
<BODY STYLE="font-family: '21st Century', fantasy">
</pre>
<p>Font family <em>names</em> that happen to be the same as a keyword value
(‘<code class=property>inherit</code>’, ‘<code class=property><a
href="#serif">serif</a></code>’, ‘<code class=property><a
href="#sans-serif">sans-serif</a></code>’, ‘<code class=property><a
href="#monospace">monospace</a></code>’, ‘<code class=property><a
href="#fantasy">fantasy</a></code>’, and ‘<code class=property><a
href="#cursive">cursive</a></code>’) must be quoted to prevent confusion
with the keywords with the same names. The keywords ‘<code
class=property>initial</code>’ and ‘<code
class=property>default</code>’ are reserved for future use and must also
be quoted when used as font names. UAs must not consider these keywords as
matching the ‘<code class=css><family-name></code>’ type.
<p>Some font formats allow fonts to carry multiple localizations of the
family name. User agents must recognize and correctly match all of these
names independent of the underlying platform localization, system API used
or document encoding:
<div class=figure><img alt="examples of localized family names"
src=localizedfamilynames.png>
<p class=caption>Localized family names
</div>
<h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
families</h4>
<p>All five generic font families are defined to exist in all CSS
implementations (they need not necessarily map to five distinct actual
fonts). User agents should provide reasonable default choices for the
generic font families, which express the characteristics of each family as
well as possible within the limits allowed by the underlying technology.
User agents are encouraged to allow users to select alternative choices
for the generic fonts.
<h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
<p>Glyphs of serif fonts, as the term is used in CSS, have finishing
strokes, flared or tapering ends, or have actual serifed endings
(including slab serifs). Serif fonts are typically proportionately-spaced.
They often display a greater variation between thick and thin strokes than
fonts from the ‘<code class=property><a
href="#sans-serif">sans-serif</a></code>’ generic font family. CSS uses
the term ‘<code class=property><a href="#serif">serif</a></code>’ to
apply to a font for any script, although other names may be more familiar
for particular scripts, such as Mincho (Japanese), Sung, Song or Kai
(Chinese), Batang (Korean). Any font that is so described may be used to
represent the generic ‘<code class=property><a
href="#serif">serif</a></code>’ family.
<div class=figure><img alt="sample serif fonts" src=serifexamples.png>
<p class=caption>Sample serif fonts
</div>
<h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
title="sans-serif, definition of"> <a name=sans-serif-def><dfn
id=sans-serif>sans-serif</dfn></a></span></h5>
<p>Glyphs in sans-serif fonts, as the term is used in CSS, have stroke
endings that are plain -- without any flaring, cross stroke, or other
ornamentation. Sans-serif fonts are typically proportionately-spaced. They
often have little variation between thick and thin strokes, compared to
fonts from the ‘<code class=property><a
href="#serif">serif</a></code>’ family. CSS uses the term ‘<code
class=property><a href="#sans-serif">sans-serif</a></code>’ to apply to
a font for any script, although other names may be more familiar for
particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
(Korean). Any font that is so described may be used to represent the
generic ‘<code class=property><a
href="#sans-serif">sans-serif</a></code>’ family.
<div class=figure><img alt="sample sans-serif fonts"
src=sansserifexamples.png>
<p class=caption>Sample sans-serif fonts
</div>
<h5 class="no-num no-toc"> <span class=index-def id=cursive0
title="cursive, definition of"> <a name=cursive-def><dfn
id=cursive>cursive</dfn></a></span></h5>
<p>Glyphs in cursive fonts generally have either joining strokes or other
cursive characteristics beyond those of italic typefaces. The glyphs are
partially or completely connected, and the result looks more like
handwritten pen or brush writing than printed letterwork. Some scripts,
such as Arabic, are almost always cursive. CSS uses the term ‘<code
class=property><a href="#cursive">cursive</a></code>’ to apply to a font
for any script, although other names such as Chancery, Brush, Swing and
Script are also used in font names.
<div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
<p class=caption>Sample cursive fonts
</div>
<h5 class="no-num no-toc"> <span class=index-def id=fantasy0
title="fantasy, definition of"> <a name=fantasy-def><dfn
id=fantasy>fantasy</dfn></a></span></h5>
<p>Fantasy fonts are primarily decorative fonts that contain playful
representations of characters. These do not include Pi or Picture fonts
which do not represent actual characters.
<div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
<p class=caption>Sample fantasy fonts
</div>
<h5 class="no-num no-toc"> <span class=index-def id=monospace0
title="monospace, definition of"> <a name=monospace-def><dfn
id=monospace>monospace</dfn></a></span></h5>
<p>The sole criterion of a monospace font is that all glyphs have the same
fixed width. This is often used to render samples of computer code.
<div class=figure><img alt="sample monospace fonts"
src=monospaceexamples.png>
<p class=caption>Sample monospace fonts
</div>
<!-- prop: font-weight -->
<h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
href="#propdef-font-weight">font-weight</a> property</h3>
<table class=propdef id=namefont-weight>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-weight>font-weight</dfn>
<tr>
<td>Value:
<td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
| 700 | 800 | 900 | inherit
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>see description
</table>
<p>The <a class=noxref href="#font-weight-prop"><span
class=property>‘<code class=property>font-weight</code>’</span></a>
property specifies weight of glyphs in the font, their degree of blackness
or stroke thickness.
<p>Values have the following meanings:
<dl>
<dt>100 to 900
<dd>These values form an ordered sequence, where each number indicates a
weight that is at least as dark as its predecessor. These roughly
correspond to the commonly used weight names below:
</dl>
<ul>
<li>100 - Thin
<li>200 - Extra Light (Ultra Light)
<li>300 - Light
<li>400 - Normal
<li>500 - Medium
<li>600 - Semi Bold (Demi Bold)
<li>700 - Bold
<li>800 - Extra Bold (Ultra Bold)
<li>900 - Black (Heavy)
</ul>
<dl>
<dt><strong>normal</strong>
<dd>Same as ‘<code class=css>400</code>’.
<dt><strong>bold</strong>
<dd>Same as ‘<code class=css>700</code>’.
<dt><strong>bolder</strong>
<dd>Specifies the weight of the face bolder than the inherited value.
<dt><strong>lighter</strong>
<dd>Specifies the weight of the face lighter than the inherited value.
</dl>
<p>Font formats that use a scale other than a nine step scale should map
their scale onto the CSS scale so that 400 roughly corresponds with a face
that would be labeled as Regular, Book, Roman and 700 roughly matches a
face that would be labeled as Bold. Or weights may be inferred from the
style names, ones that correspond roughly with the scale above. The scale
is relative, so a face with a larger weight value must never appear
lighter. If style names are used to infer weights, care should be taken to
handle variations in style names across locales.
<p>Quite often there are only a few weights available for a particular font
family. When a weight is specified for which no face exists, a face with a
nearby weight is used. In general, bold weights map to faces with heavier
weights and light weights map to faces with lighter weights (see the <a
href="#font-matching-algorithm">font matching section below</a> for a
precise definition). The examples here illustrate which face is used for
different weights, grey indicates a face for that weight does not exist so
a face with a nearby weight is used:
<div class=figure><img alt="weight mappings for a family with 400, 700 and
900 weights" src=optimaweights.png>
<p class=caption>Weight mappings for a font family with 400, 700 and 900
weight faces
</div>
<div class=figure><img alt="weight mappings for a family with 300, 600
weights" src=hiraginoweights.png>
<p class=caption>Weight mappings for a font family with 300 and 600 weight
faces
</div>
<p>Although the practice is not well-loved by typographers, bold faces are
often synthesized by user agents for faces that lack actual bold faces.
For the purposes of style matching, these faces must be treated as if they
exist within the family.
<p>Values of ‘<code class=property>bolder</code>’ and ‘<code
class=property>lighter</code>’ indicate values relative to the weight of
the parent element. Based on the inherited weight value, the weight used
is calculated using the chart below. Child elements inherit the calculated
weight, not a value of ‘<code class=property>bolder</code>’ or
‘<code class=property>lighter</code>’.
<table class=data summary="Bolder/lighter mappings">
<thead>
<tr>
<th scope=col>Inherited value
<th scope=col>bolder
<th scope=col>lighter
<tbody>
<tr>
<th>100
<td>400
<td>100
<tr>
<th>200
<td>400
<td>100
<tr>
<th>300
<td>400
<td>100
<tr>
<th>400
<td>700
<td>100
<tr>
<th>500
<td>700
<td>100
<tr>
<th>600
<td>900
<td>400
<tr>
<th>700
<td>900
<td>400
<tr>
<th>800
<td>900
<td>700
<tr>
<th>900
<td>900
<td>700
</table>
<p>The table above is equivalent to selecting the next relative bolder or
lighter face, given a font family containing normal and bold faces along
with a thin and a heavy face. Authors who desire finer control over the
exact weight values used for a given element should use numerical values
instead of relative weights.</p>
<!-- prop: font-stretch -->
<h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
href="#propdef-font-stretch">font-stretch</a> property</h3>
<table class=propdef id=namefont-stretch>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-stretch>font-stretch</dfn>
<tr>
<td>Value:
<td>normal | ultra-condensed | extra-condensed | condensed |
semi-condensed | semi-expanded | expanded | extra-expanded |
ultra-expanded | inherit
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>The <a class=noxref href="#font-stretch-prop"><span
class=property>‘<code class=property>font-stretch</code>’</span></a>
property selects a normal, condensed, or expanded face from a font family.
Absolute keyword values have the following ordering, from narrowest to
widest:
<ul>
<li>Ultra Condensed
<li>Extra Condensed
<li>Condensed
<li>Semi Condensed
<li>Normal
<li>Semi Expanded
<li>Expanded
<li>Extra Expanded
<li>Ultra Expanded
</ul>
<p>The scale is relative, so a face with a font-stretch value higher in the
list above should never appear wider. When a face does not exist for a
given width, normal or condensed values map to a narrower face, otherwise
a wider face. Conversely, expanded values map to a wider face, otherwise a
narrower face. The figure below shows how the nine font-stretch property
settings affect font selection for font family containing a variety of
widths, grey indicates a width for which no face exists and a different
width is substituted:
<div class=figure><img alt="width mappings for a family with condensed,
normal and expanded faces" src=universwidths.png>
<p class=caption>Width mappings for a font family with condensed, normal
and expanded width faces
</div>
<!-- prop: font-style -->
<h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
href="#propdef-font-style">font-style</a> property</h3>
<table class=propdef id=namefont-style>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-style>font-style</dfn>
<tr>
<td>Value:
<td>normal | italic | oblique | inherit
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>The <a class=noxref href="#font-style-prop"><span
class=property>‘<code class=property>font-style</code>’</span></a>
property allows italic or oblique faces to be selected. Italic forms are
generally cursive in nature while oblique faces are typically sloped
versions of the regular face. Oblique faces can be simulated by
artificially sloping the glyphs of the regular face. Compare the
artificially sloped renderings of Palatino ‘<code
class=property>a</code>’ and Baskerville ‘<code
class=property>N</code>’ in grey with the actual italic versions:
<div class=figure><img alt="artificial sloping vs. real italics"
src=realvsfakeitalics.png>
<p class=caption>Artificial sloping versus real italics
</div>
<p>A value of ‘<code class=property>normal</code>’ selects a face that
is classified as ‘<code class=property>normal</code>’, while ‘<code
class=property>oblique</code>’ selects a font that is labeled ‘<code
class=property>oblique</code>’. A value of ‘<code
class=property>italic</code>’ selects a font that is labeled ‘<code
class=property>italic</code>’, or, if that is not available, one labeled
‘<code class=property>oblique</code>’. If no italic or oblique faces
is available, an oblique face can by synthesized by rendering the normal
face with a sloping transformation applied.
<p>Many scripts lack the tradition of mixing a cursive form within text
rendered with a normal face. Chinese, Japanese and Korean fonts almost
always lack italic or oblique faces. Fonts that support a mixture of
scripts will sometimes omit specific scripts such as Arabic from the set
of glyphs supported in the italic face. User agents should be careful
about making character map assumptions across faces.</p>
<!-- prop: font-size -->
<h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
href="#propdef-font-size">font-size</a> property</h3>
<table class=propdef id=namefont-size>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-size>font-size</dfn>
<tr>
<td>Value:
<td><absolute-size> | <relative-size> | <length> |
<percentage> | inherit
<tr>
<td>Initial:
<td>medium
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>refer to parent element's font size
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>absolute length
</table>
<p>This property indicates the desired height of glyphs from the font. For
scalable fonts, the font-size is a scale factor applied to the EM unit of
the font. (Note that certain glyphs may bleed outside their EM box.) For
non-scalable fonts, the font-size is converted into absolute units and
matched against the declared font-size of the font, using the same
absolute coordinate space for both of the matched values. Values have the
following meanings:
<dl>
<dt><a name=x18><span class=index-def id=ltabsolute-sizegt
title="<absolute-size>::definition of">
<strong><absolute-size></strong></span></a>
<dd> An <a class=value-def
name=value-def-absolute-size><absolute-size></a> keyword refers to
an entry in a table of font sizes computed and kept by the user agent.
Possible values are:
<p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
<dt><a name=x19><span class=index-def id=ltrelative-sizegt
title="<relative-size>::definition
of"><strong><relative-size></strong></span></a>
<dd> A <a class=value-def
name=value-def-relative-size><relative-size></a> keyword is
interpreted relative to the table of font sizes and the font size of the
parent element. Possible values are:
<p> [ larger | smaller ]
<p> For example, if the parent element has a font size of ‘<code
class=property>medium</code>’, a value of ‘<code
class=property>larger</code>’ will make the font size of the current
element be ‘<code class=property>large</code>’. If the parent
element's size is not close to a table entry, the user agent is free to
interpolate between table entries or round off to the closest one. The
user agent may have to extrapolate table values if the numerical value
goes beyond the keywords.
<dt><span class=index-inst id=ltlengthgt
title="<length>"><length></span>
<dd>A length value specifies an absolute font size (that is independent of
the user agent's font table). Negative lengths are illegal.
<dt><span class=index-inst id=ltpercentagegt
title="<percentage>"><percentage> </span>
<dd>A percentage value specifies an absolute font size relative to the
parent element's font size. Use of percentage values, or values in
‘<code class=property>em</code>’s, leads to more robust and
cascadable style sheets.
</dl>
<p>The following table provides user agent's guideline for the
absolute-size scaling factor and their mapping to XHTML heading and
absolute font-sizes. The ‘<code class=property>medium</code>’ value is
used as the reference middle value. The user agent may fine-tune these
values for different fonts or different types of display devices.
<table class=data>
<thead>
<tr>
<th>CSS absolute-size values
<th>xx-small
<th>x-small
<th>small
<th>medium
<th>large
<th>x-large
<th>xx-large
<th>
<tbody>
<tr>
<th>scaling factor
<td>3/5
<td>3/4
<td>8/9
<td>1
<td>6/5
<td>3/2
<td>2/1
<td>3/1
<tr>
<th>XHTML headings
<td>h6
<td>
<td>h5
<td>h4
<td>h3
<td>h2
<td>h1
<td>
<tr>
<th>XHTML font sizes
<td>1
<td>
<td>2
<td>3
<td>4
<td>5
<td>6
<td>7
</table>
<p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
applying these guidelines should nevertheless avoid creating font-size
resulting in less than 9 pixels per EM unit on a computer display .</em>
<p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
factor between adjacent indexes was 1.5 which user experience proved to be
too large. In CSS2, the suggested scaling factor for computer screen
between adjacent indexes was 1.2 which still created issues for the small
sizes. The new scaling factor varies between each index to provide a
better readability.</em>
<p>The actual value [link to Cascading module] of this property may differ
from the computed value due a numerical value on ‘<code
class=property><a
href="#propdef-font-size-adjust">font-size-adjust</a></code>’ and the
unavailability of certain font sizes.
<p>Child elements inherit the computed <a class=noxref
href="#font-size-prop"><span class=property>‘<code
class=property>font-size</code>’</span></a> value (otherwise, the effect
of <a class=noxref href="#font-size-adjust-prop"><span
class=property>‘<code
class=property>font-size-adjust</code>’</span></a> would compound).
<div class=example>
<p style=display:none>Example(s):
<p>
<pre>p { font-size: 12pt; }
blockquote { font-size: larger }
em { font-size: 150% }
em { font-size: 1.5em }
</pre>
</div>
<!-- prop: font-size-adjust -->
<h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
<table class=propdef id=namefont-size-adjust>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
<tr>
<td>Value:
<td><number> | none | inherit
<tr>
<td>Initial:
<td>none
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>For any given font size, the apparent size and legibility of text varies
across fonts. For scripts such as Latin or Cyrillic that distinguish
between upper and lowercase letters, the relative height of lowercase
letters compared to their uppercase counterparts is a determining factor
of legibility. This is commonly referred to as the <a class=index-def
href="#aspect" id=aspect0 title="aspect value"><dfn id=aspect>aspect
value</dfn></a>. Precisely defined, it is equal to the x-height of a font
divided by the font size.
<p>In situations where font fallback occurs, fallback fonts may not share
the same aspect ratio as the desired font family and will thus appear less
readable. The font-size-adjust property is a way to preserve the
readability of text when font fallback occurs. It does this by adjusting
the font-size so that the x-height is the same regardless of the font
used.
<div class=example>
<p>The style defined below defines Verdana as the desired font family, but
if Verdana is not available Futura or Times will be used.</p>
<pre>p {
font-family: Verdana, Futura, Times;
}
<p>Lorem ipsum dolor sit amet, ...</p>
</pre>
<p>Verdana has a relatively high aspect ratio, lowercase letters are
relatively tall compared to uppercase letters, so at small sizes text
appears legible. Times has a lower aspect ratio and so if fallback
occurs, the text will be less legible at small sizes than Verdana.</p>
</div>
<p>How text rendered in each of these fonts compares is shown below, the
columns show text rendered in Verdana, Futura and Times. The same
font-size value is used across cells within each row and red lines are
included to show the differences in x-height. In the upper half each row
is rendered in the same font-size value. The same is true for the lower
half but in this half the font-size-adjust property is also set so that
the actual font size is adjusted to preserve the x-height across each row.
Note how small text remains relatively legible across each row in the
lower half.
<div class=figure><img alt="text with and without font-size-adjust"
src=fontsizeadjust.png>
<p class=caption>Text with and without the use of font-size-adjust
</div>
<p>This property allows authors to specify an aspect value for an element
that will effectively preserve the x-height of the first choice font,
whether it is substituted or not. Values have the following meanings:
<dl>
<dt><strong>none</strong>
<dd>Do not preserve the font's x-height.
<dt><span class=index-inst id=ltnumbergt
title="<number>"><number></span>
<dd>Specifies the aspect value used in the calculation below to calculate
the adjusted font size:
<pre>c = ( a / a' ) s
</pre>
<p>where:</p>
<pre>s = font-size value
a = aspect value as specified by the font-size-adjust property
a' = aspect value of actual font
c = adjusted font-size to use
</pre>
<p>This value applies to any font that is selected but in typical usage
it should be based on the aspect value of the first font in the
font-family list. If this is specified accurately, the <tt>(a/a')</tt>
term in the formula above is effectively 1 for the first font and no
adjustment occurs. If the value is specified inaccurately, text rendered
using the first font in the family list will display differently in
older user agents that don't support font-size-adjust.</p>
</dl>
<p>Authors can calculate the aspect value for a given font by comparing
spans with the same content but different font-size-adjust properties. If
the same font-size is used, the spans will match when the font-size-adjust
value is accurate for the given font.
<div class=example>
<p>Two spans with borders are used to determine the aspect value of a
font. The font-size is the same for both spans but the font-size-adjust
property is specified only for the right span. Starting with a value of
0.5, the aspect value can be adjusted until the borders around the two
letters line up.</p>
<pre>p {
font-family: Futura;
font-size: 500px;
}
span {
border: solid 1px red;
}
.adjust {
font-size-adjust: 0.5;
}
<p><span>b</span><span class="adjust">b</span></p>
</pre>
<div class=figure><img alt="Futura with an aspect value of 0.5"
src=beforefontsizeadjust.png>
<p class=caption>Futura with an aspect value of 0.5
</div>
<p>The box on the right is a bit bigger than the one on the left, so the
aspect value of this font is something less than 0.5. Adjust the value
until the boxes align.</p>
</div>
<!-- Hmm, so what should happen for scripts with no upper/lowercase distinction (e.g. CJK, Arabic, Hebrew)? -->
<!-- prop: font -->
<!-- jtdfix, crap, preprocessor is inserting links to descriptors rather than properties. bert, make it stop... -->
<h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
<a href="#propdef-font">font</a> property</h3>
<table class=propdef id=namefont>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font>font</dfn>
<tr>
<td>Value:
<td>[ [ <‘<code class=property><a
href="#descdef-font-style">font-style</a></code>’> ||
<font-variant-css21> || <‘<code class=property><a
href="#descdef-font-weight">font-weight</a></code>’> ]? <‘<code
class=property><a href="#propdef-font-size">font-size</a></code>’> [
/ <‘<code class=property>line-height</code>’> ]? <‘<code
class=property><a
href="#descdef-font-family">font-family</a></code>’> ] | caption |
icon | menu | message-box | small-caption | status-bar | inherit
<tr>
<td>Initial:
<td>see individual properties
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>see individual properties
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>see individual properties
</table>
<p>The <span class=property>‘<code class=property><a
href="#propdef-font">font</a></code>’</span> property is, except as
described below, a shorthand property for setting ‘<code
class=property><a href="#descdef-font-style">font-style</a></code>’,
<span class=property>‘<code class=property><a
href="#propdef-font-variant">font-variant</a></code>’</span>, <span
class=property>‘<code class=property><a
href="#descdef-font-weight">font-weight</a></code>’</span>, <span
class=property>‘<code class=property><a
href="#propdef-font-size">font-size</a></code>’</span>, ‘<code
class=property>line-height</code>’, <span class=property>‘<code
class=property><a
href="#descdef-font-family">font-family</a></code>’</span> at the same
place in the stylesheet. Values for the <span class=property>‘<code
class=property><a
href="#propdef-font-variant">font-variant</a></code>’</span> property
may also be included but only those supported in CSS 2.1, none of the
font-variant values added in this specification can be used in the <span
class=property>‘<code class=property><a
href="#propdef-font">font</a></code>’</span> shorthand:
<pre
class=prod><dfn id=ltfont-variant-css21gt><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
<p>The syntax of this property is based on a traditional typographical
shorthand notation to set multiple properties related to fonts.
<p>All font-related properties are first reset to their initial values,
including those listed in the preceding paragraph plus <span
class=property>‘<code class=property><a
href="#descdef-font-stretch">font-stretch</a></code>’</span>, <span
class=property>‘<code class=property><a
href="#propdef-font-size-adjust">font-size-adjust</a></code>’</span>,
<span class=property>‘<code class=property><a
href="#propdef-font-kerning">font-kerning</a></code>’</span> and all
font feature properties. Then, those properties that are given explicit
values in the <span class=property>‘<code class=property><a
href="#propdef-font">font</a></code>’</span> shorthand are set to those
values. For a definition of allowed and initial values, see the previously
defined properties. For reasons of backwards compatibility, it is not
possible to set <span class=property>‘<code class=property><a
href="#descdef-font-stretch">font-stretch</a></code>’</span> and <span
class=property>‘<code class=property><a
href="#propdef-font-size-adjust">font-size-adjust</a></code>’</span> to
other than their initial values using the <span class=property>‘<code
class=property><a href="#propdef-font">font</a></code>’</span> shorthand
property; instead, set the individual properties.
<div class=example>
<p style=display:none>Example(s):
<p>
<pre>p { font: 12pt/14pt sans-serif }
p { font: 80% sans-serif }
p { font: x-large/110% "new century schoolbook", serif }
p { font: bold italic large Palatino, serif }
p { font: normal small-caps 120%/120% fantasy }
p { font: oblique 12pt "Helvetica Neue", serif; font-stretch: condensed }
</pre>
<p> In the second rule, the font size percentage value (‘<code
class=css>80%</code>’) refers to the font size of the parent element.
In the third rule, the line height percentage (‘<code
class=css>110%</code>’) refers to the font size of the element itself.
<p>The first three rules do not specify the <span class=property>‘<code
class=property><a
href="#propdef-font-variant">font-variant</a></code>’</span> and <span
class=property>‘<code class=property><a
href="#descdef-font-weight">font-weight</a></code>’</span> explicitly,
so these properties receive their initial values (‘<code
class=property>normal</code>’). Notice that the font family name "new
century schoolbook", which contains spaces, is enclosed in quotes. The
fourth rule sets the <span class=property>‘<code class=property><a
href="#descdef-font-weight">font-weight</a></code>’</span> to ‘<code
class=property>bold</code>’, the <span class=property>‘<code
class=property><a
href="#descdef-font-style">font-style</a></code>’</span> to ‘<code
class=property>italic</code>’, and implicitly sets <span
class=property>‘<code class=property><a
href="#propdef-font-variant">font-variant</a></code>’</span> to
‘<code class=property>normal</code>’.
<p> The fifth rule sets the <span class=property>‘<code
class=property><a
href="#propdef-font-variant">font-variant</a></code>’</span> (‘<code
class=property><a href="#small-caps">small-caps</a></code>’), the <span
class=property>‘<code class=property><a
href="#propdef-font-size">font-size</a></code>’</span> (120% of the
parent's font size), the <span class=property>‘<code
class=property>line-height</code>’</span> (120% of the font size) and
the <span class=property>‘<code class=property><a
href="#descdef-font-family">font-family</a></code>’</span> (‘<code
class=property><a href="#fantasy">fantasy</a></code>’). It follows that
the keyword ‘<code class=property>normal</code>’ applies to the two
remaining properties: <span class=property>‘<code class=property><a
href="#descdef-font-style">font-style</a></code>’</span> and <span
class=property>‘<code class=property><a
href="#descdef-font-weight">font-weight</a></code>’</span>.
<p>The sixth fifth rule sets the <span class=property>‘<code
class=property><a
href="#descdef-font-style">font-style</a></code>’</span>, <span
class=property>‘<code class=property><a
href="#propdef-font-size">font-size</a></code>’</span>, and <span
class=property>‘<code class=property><a
href="#descdef-font-family">font-family</a></code>’</span>, the other
font properties being set to their initial values. It then sets <span
class=property>‘<code class=property><a
href="#descdef-font-stretch">font-stretch</a></code>’</span> to
‘<code class=property>condensed</code>’ since that property cannot be
set to that value using the <span class=property>‘<code
class=property><a href="#propdef-font">font</a></code>’</span>
shorthand property.
</div>
<p>The following values refer to system fonts:
<dl>
<dt><strong>caption</strong>
<dd>The font used for captioned controls (e.g., buttons, drop-downs,
etc.).
<dt><strong>icon</strong>
<dd>The font used to label icons.
<dt><strong>menu</strong>
<dd>The font used in menus (e.g., dropdown menus and menu lists).
<dt><strong>message-box</strong>
<dd>The font used in dialog boxes.
<dt><strong>small-caption</strong>
<dd>The font used for labeling small controls.
<dt><strong>status-bar</strong>
<dd>The font used in window status bars.
</dl>
<p>System fonts may only be set as a whole; that is, the font family, size,
weight, style, etc. are all set at the same time. These values may then be
altered individually if desired. If no font with the indicated
characteristics exists on a given platform, the user agent should either
intelligently substitute (e.g., a smaller version of the ‘<code
class=property>caption</code>’ font might be used for the ‘<code
class=property>smallcaption</code>’ font), or substitute a user agent
default font. As for regular fonts, if, for a system font, any of the
individual properties are not part of the operating system's available
user preferences, those properties should be set to their initial values.
<p>That is why this property is "almost" a shorthand property: system fonts
can only be specified with this property, not with <span
class=property>‘<code class=property><a
href="#descdef-font-family">font-family</a></code>’</span> itself, so
<span class=property>‘<code class=property><a
href="#propdef-font">font</a></code>’</span> allows authors to do more
than the sum of its subproperties. However, the individual properties such
as <span class=property>‘<code class=property><a
href="#descdef-font-weight">font-weight</a></code>’</span> are still
given values taken from the system font, which can be independently
varied.
<div class=example>
<p style=display:none>Example(s):
<p>
<pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
button p { font: menu }
button p em { font-weight: bolder }
</pre>
<p>If the font used for dropdown menus on a particular system happened to
be, for example, 9-point Charcoal, with a weight of 600, then P elements
that were descendants of BUTTON would be displayed as if this rule were
in effect:
<pre>button p { font: 600 9pt Charcoal }
</pre>
<p>Because the <span class=property>‘<code class=property><a
href="#propdef-font">font</a></code>’</span> shorthand resets to its
initial value any property not explicitly given a value, this has the
same effect as this declaration:
<pre>button p {
font-style: normal;
font-variant: normal;
font-weight: 600;
font-size: 9pt;
line-height: normal;
font-family: Charcoal
}
</pre>
</div>
<!-- prop: font-synthesis -->
<h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
property</h3>
<table class=propdef id=namefont-synthesis>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
<tr>
<td>Value:
<td>none | [ weight || style ]
<tr>
<td>Initial:
<td>weight style
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>This property controls whether user agents are allowed to synthesize
bold or oblique font faces when a font family lacks bold or italic faces.
If ‘<code class=property>weight</code>’ is not specified, user agents
must not synthesize bold faces and if ‘<code
class=property>style</code>’ is not specified user agents must not
synthesize italic faces. A value of ‘<code class=property>none</code>’
disallows all synthetic faces.
<div class=example>
<p>The style rule below disables the use of synthetically obliqued Arabic:</p>
<pre>*:lang(ar) { font-synthesis: none; }
</pre>
</div>
<h2 id=font-resources><span class=secno>4 </span>Font resources</h2>
<h3 id=font-face-rule><span class=secno>4.1 </span>The @font-face rule</h3>
<p>The @font-face rule allows for linking to fonts that are automatically
activated when needed. This allows authors to select a font that closely
matches the design goals for a given page rather than limiting the font
choice to a set of fonts available on all platforms. A set of font
descriptors define the location of a font resource, either locally or
externally, along with the style characteristics of an individual face.
Multiple @font-face rules can be used to construct font families with a
variety of faces. Using CSS font matching rules, a user agent can
selectively download only those faces that are needed for a given piece of
text.
<p>The general form of an <span class=index-def id=font-face
title="@font-face"><em>@font-face</em></span> <span class=index-inst
id=at-rule title=at-rules>at-rule</span> is:
<pre>
@font-face { <span class=value-inst-font-description><font-description></span> }
</pre>
<p>where <span class=index-def id=ltfont-descriptiongt
title="<font-description>::definition of"><a
name=value-def-font-description><font-description></a></span> has
the form:
<pre>
descriptor: value;
descriptor: value;
[...]
descriptor: value;
</pre>
<p>Each <span class=index-inst id=font-face0
title="@font-face">@font-face</span> rule specifies a value for every font
descriptor, either implicitly or explicitly. Those not given explicit
values in the rule take the initial value listed with each descriptor in
this specification. These descriptors apply solely within the context of
the @font-face rule in which they are defined, and do not apply to
document language elements. There is no notion of which elements the
descriptors apply to or whether the values are inherited by child
elements. When a given descriptor occurs multiple times in a given
@font-face rule, only the last specified value is used, all prior values
for that descriptor are ignored.
<div class=example>
<p>To use a downloadable font called Gentium:</p>
<pre>
@font-face {
font-family: Gentium;
src: url(http://example.com/fonts/Gentium.ttf);
}
p { font-family: Gentium, serif; }
</pre>
<p>The user agent will download Gentium and use it when rendering text
within paragraph elements. If for some reason the site serving the font
is unavailable, the default serif font will be used.</p>
</div>
<p>A given set of @font-face rules define a set of fonts available to
containing documents. Multiple rules can be used to define a family with a
large set of faces. When font matching is done fonts defined using these
rules are considered before other available fonts on a system.
<p>Downloaded fonts are only available to documents that reference them,
the process of activating these fonts should not make them available to
other applications or to documents that don't directly link to the same
font. User agent implementers might consider it convenient to use
downloaded fonts when rendering characters in other documents for which no
other available font exists as part of the system font fallback procedure.
This would cause a security leak since the contents of one page would be
able to affect other pages, something an attacker could use as an attack
vector. These restrictions do not affect caching behavior, fonts are
cached the same way other web resources are cached.
<p>User agents which do not understand the @font-face rule encounter the
opening curly bracket and ignore forward until the closing curly bracket.
This at-rule conforms with the forward-compatible parsing requirement of
CSS, parsers may ignore these rules without error. Any descriptors that
are not recognized or implemented by a given user agent must be ignored.
@font-face rules require a font-family and src descriptor, if either of
these are missing the @font-face must be ignored.
<p>In cases where user agents have limited platform resources or implement
the ability to disable downloadable font resources, @font-face rules must
simply be ignored; the behavior of individual descriptors as defined in
this specification should not be altered.
<h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
href="#descdef-font-family">font-family</a> descriptor</h3>
<table class=descdef>
<tbody>
<tr>
<td>Name:
<td><dfn id=descdef-font-family>font-family</dfn>
<tr>
<td>Value:
<td><family-name>
<tr>
<td><em>Initial:</em>
<td>N/A
</table>
<p>This descriptor defines the font family name that will be used in all
CSS font family name matching, overriding font family names contained in
the underlying font data. If the font family name is the same as a font
family available in a given user's environment, it effectively hides the
underlying font for documents that use the stylesheet. This permits a web
author to freely choose font-family names without worrying about conflicts
with font family names present in a given user's environment. Errors
loading font data do not affect font name matching behavior. User agents
that apply platform font aliasing rules to font family names defined via
@font-face rules are considered non-conformant.
<h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
href="#descdef-src">src</a> descriptor</h3>
<table class=descdef>
<tbody>
<tr>
<td>Name:
<td><dfn id=descdef-src>src</dfn>
<tr>
<td>Value:
<td>[ <uri> [format(<string> [, <string>]*)] |
<font-face-name> ] [, <uri> [format(<string> [,
<string>]*)] | <font-face-name> ]*
<tr>
<td><em>Initial:</em>
<td>N/A
</table>
<p>This descriptor specifies the resource containing font data. It is
required, whether the font is downloadable or locally installed. Its value
is a prioritized, comma-separated list of external references or locally
installed font face names. When a font is needed the user agent iterates
over the set of references listed, using the first one it can successfully
activate. Fonts containing invalid data or local font faces that are not
found are ignored and the user agent loads the next font in the list
(platform substitutions for a given font must not be used).
<p>As with other URIs in CSS, the URI may be partial, in which case it is
resolved relative to the location of the style sheet containing the <span
class=index-inst id=font-face1 title="@font-face">@font-face</span> rule.
In the case of SVG fonts, the URL points to an element within a document
containing SVG font definitions. If the element reference is omitted, a
reference to the first defined font is implied.
<pre>
src: url(fonts/simple.ttf); /* load simple.ttf relative to stylesheet location */
src: url(/fonts/simple.ttf); /* load simple.ttf from absolute location */
src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
</pre>
<p>External references consist of a URI, followed by an optional hint
describing the format of the font resource referenced by that URI. The
format hint contains a comma-separated list of format strings that denote
well-known font formats. Conformant user agents must skip downloading a
font resource if the format hints indicate only unsupported or unknown
font formats. If no format hints are supplied, the user agent should
download the font resource.
<pre>
/* load WOFF font if possible, otherwise use OpenType font */
@font-face {
font-family: bodytext;
src: url(ideal-sans-serif.woff) format("woff"),
url(basic-sans-serif.ttf) format("opentype");
}
</pre>
<p>Format strings defined by this specification:
<table class=data id=fontformats>
<thead>
<tr>
<th>String
<th>Font Format
<th>Common extensions
<tbody>
<tr>
<th>"woff"
<td>WOFF (Web Open Font Format)
<td>.woff
<tr>
<th>"truetype"
<td>TrueType
<td>.ttf
<tr>
<th>"opentype"
<td>OpenType
<td>.ttf, .otf
<tr>
<th>"embedded-opentype"
<td>Embedded OpenType
<td>.eot
<tr>
<th>"svg"
<td>SVG Font
<td>.svg, .svgz
</table>
<p>Given the overlap in common usage between TrueType and OpenType, the
format hints "truetype" and "opentype" must be considered as synonymous; a
format hint of "opentype" does not imply that the font contains Postscript
CFF style glyph data or that it contains OpenType layout information (see
Appendix A for more background on this).
<p>When authors would prefer to use a locally available copy of a given
font and download it if it's not, local() can be used. The locally
installed <span class=index-def id=ltfont-face-namegt
title="<font-face-name>::definition of"><a
name=value-def-font-face-name><font-face-name></a></span> is a
format-specific string that uniquely identifies a single font face within
a larger family. The syntax for a <font-face-name> is a unique font
face name enclosed by "local(" and ")".
<pre>
/* regular face of Gentium */
@font-face {
font-family: MyGentium;
src: local(Gentium), /* use locally available Gentium */
url(Gentium.ttf); /* otherwise, download it */
}
</pre>
<p>The name can optionally be enclosed in quotes. For OpenType and TrueType
fonts, this string is used to match only the Postscript name or the full
font name in the name table of locally available fonts. Which is used
varies by platform and font, so authors should include both of these names
to assure proper matching across platforms.
<pre>
/* bold face of Gentium */
@font-face {
font-family: MyGentium;
src: local(Gentium Bold), /* full font name */
local(Gentium-Bold), /* Postscript name */
url(GentiumBold.ttf); /* otherwise, download it */
font-weight: bold;
}
</pre>
<p>Just as a @font-face rule specifies the characteristics of a single font
within a family, the unique name used with local() specifies a single
font, not an entire font family. Defined in terms of OpenType font data,
the Postscript name is found in the font's <a
href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
in the name record with nameID = 6 (see <a href="#OPENTYPE"
rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
Postscript name is the commonly used key for all fonts on OSX and for
Postscript CFF fonts under Windows. The full font name (nameID = 4) is
used as a unique key for fonts with TrueType glyphs on Windows.
<p>For OpenType fonts with multiple localizations of the full font name,
the US English version is used (language ID = 0x409 for Windows and
language ID = 0 for Macintosh) or the first localization when a US English
full font name is not available (the OpenType specification recommends
that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
fonts minimally include US English names</a>). User agents that also match
other full font names, e.g. matching the Dutch name when the current
system locale is set to Dutch, are considered non-conformant. This is done
not to prefer English but to avoid matching inconsistencies across font
versions and OS localizations, since font style names (e.g. "Bold") are
frequently localized into many languages and the set of localizations
available varies widely across platform and font version. User agents that
match a concatenation of family name (nameID = 1) with style name (nameID
= 2) are considered non-conformant.
<p>This also allows for referencing faces that belong to larger families
that cannot otherwise be referenced.
<div class=example>
<p>Use a local font or reference an SVG font in another document:</p>
<pre>
@font-face {
font-family: Headline;
src: local(Futura-Medium),
url(fonts.svg#MyGeometricModern) format("svg");
}
</pre>
<p>Create an alias for local Japanese fonts on different platforms:</p>
<pre>
@font-face {
font-family: jpgothic;
src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
}
</pre>
<p>Reference a font face that cannot be matched within a larger family:</p>
<pre>
@font-face {
font-family: Hoefler Text Ornaments;
/* has the same font properties as Hoefler Text Regular */
src: local(HoeflerText-Ornaments);
}
</pre>
<p>Since localized fullnames should never match, a document with the
header style rules below would always render using the default serif
font, regardless whether a particular system locale parameter is set to
Finnish or not:</p>
<pre>
@font-face {
font-family: SectionHeader;
src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, matching should fail */
font-weight: bold;
}
h2 { font-family: SectionHeader, serif; }
</pre>
<p>A conformant user agent should never load the font ‘<code
class=css>gentium.eot</code>’ in the example below, since it is
included in the first definition of the ‘<code class=property><a
href="#descdef-src">src</a></code>’ descriptor which is overridden by
the second definition in the same @font-face rule:</p>
<pre>
@font-face {
font-family: MainText;
src: url(gentium.eot); /* for compatibility with older non-conformant user agents */
src: local("Gentium"), url(gentium.ttf); /* Overrides src definition */
}
</pre>
</div>
<h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
descriptors: the <a href="#descdef-font-style">font-style</a>, <a
href="#descdef-font-weight">font-weight</a>, <a
href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
<table class=descdef>
<tbody>
<tr>
<td>Name:
<td><dfn id=descdef-font-style>font-style</dfn>
<tr>
<td>Value:
<td>normal | italic | oblique
<tr>
<td><em>Initial:</em>
<td>normal
</table>
<table class=descdef>
<tbody>
<tr>
<td>Name:
<td><dfn id=descdef-font-weight>font-weight</dfn>
<tr>
<td>Value:
<td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
<tr>
<td><em>Initial:</em>
<td>normal
</table>
<table class=descdef>
<tbody>
<tr>
<td>Name:
<td><dfn id=descdef-font-stretch>font-stretch</dfn>
<tr>
<td>Value:
<td>normal | ultra-condensed | extra-condensed | condensed |
semi-condensed | semi-expanded | expanded | extra-expanded |
ultra-expanded
<tr>
<td><em>Initial:</em>
<td>normal
</table>
<p>These descriptors define the characteristics of a font face and are used
in the process of matching styles to specific faces. For a font family
defined with several @font-face rules, user agents can either download all
faces in the family or use these descriptors to selectively download font
faces that match actual styles used in document. The values for these
descriptors are the same as those for the corresponding font properties
except that relative keywords are not allowed, ‘<code
class=property>bolder</code>’ and ‘<code
class=property>lighter</code>’. If these descriptors are omitted,
default values are assumed.
<p>The value for these font face style attributes is used in place of the
style implied by the underlying font data. This allows authors to combine
faces in flexible combinations, even in situations where the original font
data was arranged differently. User agents that implement synthetic
bolding and obliqueing must only apply synthetic styling in cases where
the font descriptors imply this is needed, rather than based on the style
attributes implied by the font data.
<h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
<a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
<table class=descdef>
<tbody>
<tr>
<td>Name:
<td><dfn id=descdef-unicode-range>unicode-range</dfn>
<tr>
<td>Value:
<td><urange> [, <urange>]*
<tr>
<td><em>Initial:</em>
<td>U+0-10FFFF
</table>
<p>This descriptor defines the range of Unicode characters supported by a
given font. The values of <span class=index-def id=lturangegt
title="<urange>::definition of"><a
name=value-def-urange><urange></a></span> are expressed using
hexadecimal numbers prefixed by "U+", corresponding to <a
href="http://www.unicode.org/charts/">Unicode character code points</a>.
The unicode-range descriptor serves as a hint for user agents when
deciding whether or not to download a font resource.
<p>Unicode range values are written using hexadecimal values and are case
insensitive. Each is prefixed by "U+" and multiple, discontinuous ranges
are separated by commas. Whitespace before or after commas is ignored.
Valid character code values vary between 0 and 10FFFF inclusive. A single
range has three basic forms:
<ul>
<li>a single code point (e.g. U+416)
<li>an interval value range (e.g. U+400-4ff)
<li>a range where trailing ‘<code class=css>?</code>’ characters imply
‘<code class=css>any digit value</code>’ (e.g. U+4??)
</ul>
<p>Ranges that do not fit any of the above three forms are considered to be
parse errors and the descriptor is omitted. Interval ranges consisting of
a single code point are valid. Ranges specified with ‘?’ that lack an
initial digit (e.g. "U+???") are also valid, and are treated as if there
was a single 0 before the question marks (thus, "U+???" = "U+0???" =
"U+0000-0FFF"). "U+??????" is not a syntax error, even though "U+0??????"
would be. Ranges can overlap but interval ranges that descend (e.g.
U+400-32f) are invalid and omitted rather than treated as parse errors;
they have no effect on other ranges in a list of ranges. Ranges are
clipped to the domain of Unicode code points (currently 0 - 10FFFF
inclusive); a range entirely outside the domain is omitted. Without any
valid ranges, the descriptor is omitted. User agents may normalize the
list of ranges into a list that is different but represents the same set
of character code points.
<p>The character range can be a subset of the full character map of the
underlying font. The effective unicode-range used when mapping characters
to fonts is the intersection of the unicode range specified and the
underlying character map of the font. This means that authors do not need
to define the unicode-range of a font precisely, broad ranges for which a
sparse set of code points are defined in the font can be used. Code points
outside of the defined unicode-range are ignored, regardless of whether
the font contains a glyph for that code point or not. User agents that
download fonts for characters outside the defined unicode-range are
considered non-conformant. Likewise, user agents that render a character
using a font resource for which the defined unicode-range does not include
that character are also considered non-conformant.
<p>Example ranges for specific languages or characters:
<dl>
<dt>unicode-range: U+A5;
<dd>a single code point, the yen/yuan symbol
<dt>unicode-range: U+0-7F;
<dd>code range for basic ASCII characters
<dt>unicode-range: U+590-5ff;
<dd>code range for Hebrew characters
<dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
<dd>code range for Japanese kanji, hiragana and katakana characters plus
yen/yuan symbol
</dl>
<div class=example>
<p>The BBC provides news services in a wide variety of languages, many
that are not well supported across all platforms. Using an @font-face
rule, the BBC could provide a font for any of these languages, as it
already does via a manual font download.</p>
<pre>
@font-face {
font-family: BBCBengali;
src: url(fonts/BBCBengali.ttf) format("opentype");
unicode-range: U+00-FF, U+980-9FF;
}
</pre>
</div>
<div class=example>
<p>Technical documents often require a wide range of symbols. The STIX
Fonts project is one project aimed at providing fonts to support a wide
range of technical typesetting in a standardized way. The example below
shows the use of a font that provides glyphs for many of the mathematical
and technical symbol ranges within Unicode:</p>
<pre>
@font-face {
font-family: STIXGeneral;
src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
}
</pre>
</div>
<p>Multiple @font-face rules with different unicode ranges for the same
family and style descriptor values can be used to create composite fonts
that mix the glyphs from different fonts for different scripts. This can
be used to combine fonts that only contain glyphs for a single script
(e.g. Latin, Greek, Cyrillic) or it can be used by authors as a way of
segmenting a font into fonts for commonly used characters and less
frequently used characters. Since the user agent will only pull down the
fonts it needs this helps reduce page bandwidth.
<p class=issue>It has been suggested that named ranges for commonly used
ranges be defined. Is this useful and if so, what should those ranges be
based on (e.g. Unicode's block definitions)? This would be especially
helpful for CJK segmenting where the goal would be to have named ranges
that group codepoints by relative frequency but it's unclear what source
to use as a basis for specifying this.
<p>If the unicode ranges overlap for a set of @font-face rules with the
same family and style descriptor values, the rules are ordered in the
reverse order they were defined; the last rule defined is the first to be
checked for a given character.
<div class=example>
<p>This example shows how an author can override the glyphs used for Latin
characters in a Japanese font with glyphs from a different font. The
first rule specifies no range so it defaults to the entire range. The
range specified in the second rule overlaps but takes precedence because
it is defined later.</p>
<pre>
@font-face {
font-family: JapaneseWithGentium;
src: local(MSMincho);
/* no range specified, defaults to entire range */
}
@font-face {
font-family: JapaneseWithGentium;
src: url(../fonts/Gentium.ttf);
unicode-range: U+0-2FF;
}
</pre>
</div>
<div class=example>
<p>Consider a family constructed to optimize bandwidth by separating out
Latin, Japanese and other characters into different font files:</p>
<pre>
/* fallback font - size: 4.5MB */
@font-face {
font-family: DroidSans;
src: url(DroidSansFallback.ttf);
/* no range specified, defaults to entire range */
}
/* Japanese glyphs - size: 1.2MB */
@font-face {
font-family: DroidSans;
src: url(DroidSansJapanese.ttf);
unicode-range: U+3000-9FFF, U+ff??;
}
/* Latin, Greek, Cyrillic along with some
punctuation and symbols - size: 190KB */
@font-face {
font-family: DroidSans;
src: url(DroidSans.ttf);
unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
}
</pre>
<p>For simple Latin text, only the font for Latin characters is
downloaded:</p>
<pre>
body { font-family: DroidSans; }
<p>This is that</p>
</pre>
<p>In this case the user agent first checks the unicode-range for the font
containing Latin characters (DroidSans.ttf). Since all the characters
above are in the range U+0-5FF, the user agent downloads the font and
renders the text with that font.</p>
<p>Next, consider text that makes use of an arrow character (⇨):</p>
<pre>
<p>This &#x21e8; that<p>
</pre>
<p>The user agent again first checks the unicode-range of the font
containing Latin characters. Since U+2000-2300 includes the arrow code
point (U+21E8), the user agent downloads the font. For this character
however the Latin font does not have a matching glyph, so the effective
unicode-range used for font matching excludes this code point. Next, the
user agent evaluates the Japanese font. The unicode-range for the
Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
user agent does not download the Japanese font. Next the fallback font is
considered. The @font-face rule for the fallback font does not define
unicode-range so its value defaults to the range of all Unicode code
points. The fallback font is downloaded and used to render the arrow
character.</p>
</div>
<!--
Tools to create subsetted fonts a problem.
Also, combining diacritics represent a nasty side issue here.
-->
<h3 id=font-rend-desc><span class=secno>4.6 </span>Font features: the <a
href="#descdef-font-variant">font-variant</a> and <a
href="#descdef-font-feature-settings">font-feature-settings</a>
descriptors</h3>
<table class=descdef>
<tbody>
<tr>
<td>Name:
<td><dfn id=descdef-font-variant>font-variant</dfn>
<tr>
<td>Value:
<td>normal | [ <common-lig-values> ||
<discretionary-lig-values> || <historical-lig-values> ||
<contextual-alt-values> || stylistic(<feature-value-name>)
|| historical-forms || styleset(<feature-value-name> [,
<feature-value-name>]*) ||
character-variant(<feature-value-name>
[,<feature-value-name>]*) || swash(<feature-value-name>) ||
ornaments(<feature-value-name>) ||
annotation(<feature-value-name>) || ruby || <caps-value> ||
<numeric-figure-values> || <numeric-spacing-values> ||
<numeric-fraction-values> || slashed-zero ||
<east-asian-variant-values> || <east-asian-width-values> ]
<tr>
<td><em>Initial:</em>
<td>normal
</table>
<table class=descdef>
<tbody>
<tr>
<td>Name:
<td><dfn id=descdef-font-feature-settings>font-feature-settings</dfn>
<tr>
<td>Value:
<td>normal | <feature-tag-value> [, <feature-tag-value>]*
<tr>
<td><em>Initial:</em>
<td>normal
</table>
<p>These descriptors define settings that apply when the font defined by an
@font-face rule is rendered. They do not affect font selection. Values are
identical to those defined for the corresponding ‘<code
class=property><a href="#propdef-font-variant">font-variant</a></code>’
and ‘<code class=property><a
href="#propdef-font-feature-settings">font-feature-settings</a></code>’
properties defined below except that the value ‘<code
class=property>inherit</code>’ is omitted. When multiple font feature
descriptors or properties are used, the cumulative effect on text
rendering is described below.
<h3 id=font-face-loading><span class=secno>4.7 </span>Font loading
guidelines</h3>
<p>The @font-face rule is designed to allow lazy loading of fonts, fonts
are only downloaded when needed for use within a document. A stylesheet
can include @font-face rules for a library of fonts of which only a select
set are used; user agents must only download those fonts that are referred
to within the style rules applicable to a given page. User agents that
download all fonts defined in @font-face rules without considering whether
those fonts are in fact used within a page are considered non-conformant.
In cases where a font might be downloaded in character fallback cases,
user agents may download a font if it's listed in a font list but is not
actually used for a given text run.
<pre>
@font-face {
font-family: GeometricModern;
src: url(font.ttf);
}
p {
/* font will be downloaded for pages with p elements */
font-family: GeometricModern, sans-serif;
}
h2 {
/* font may be downloaded for pages with h2 elements, even if Futura is available locally */
font-family: Futura, GeometricModern, sans-serif;
}
</pre>
<p>In cases where textual content is loaded before downloadable fonts are
available, user agents may render text as it would be rendered if
downloadable font resources are not available or they may render text
transparently with fallback fonts to avoid a flash of text using a
fallback font. In cases where the font download fails user agents must
display text, simply leaving transparent text is considered non-conformant
behavior. Authors are advised to use fallback fonts in their font lists
that closely match the vertical metrics of the downloadable fonts to avoid
large page reflows where possible.
<h3 id=same-origin-restriction><span class=secno>4.8 </span>Same-origin
restriction for fonts</h3>
<h4 id=default-same-origin-restriction><span class=secno>4.8.1
</span>Default same-origin restriction</h4>
<p>User agents must implement a same-origin restriction when loading fonts
via the @font-face mechanism. This restriction limits the loading of fonts
for a given document to fonts loaded from the same origin. Fonts can only
be loaded via the same host, port, and method combination as the
containing document, using the <a
href="http://www.w3.org/TR/html5/origin-0.html">origin matching
algorithm</a> described in the <a href="#HTML5"
rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
the stylesheet containing @font-face rules is not used when deciding
whether a font is same origin or not, only the origin of the containing
document is used. The restriction applies to all font types.
<p class=issue>Some implementers would prefer to define a new mechanism
(tentatively named From-Origin) to control access to all resource types,
in preference to the origin matching algorithm referred to here. As such,
this subsection should be considered at risk for alteration if such an
alternative mechanism is defined.
<p>Given a document located at http://example.com/page.html, fonts defined
with ‘<code class=property><a href="#descdef-src">src</a></code>’
definitions considered cross origin must not be loaded:
<pre>
/* same origin (i.e. domain, protocol, port match document) */
src: url(fonts/simple.ttf);
src: url(//fonts/simple.ttf);
/* cross origin, different protocol */
src: url(https://example.com/fonts/simple.ttf);
/* cross origin, different domain */
src: url(http://another.example.com/fonts/simple.ttf);
</pre>
<h4 id=allowing-cross-origin-font-loading><span class=secno>4.8.2
</span>Allowing cross-origin font loading</h4>
<p>User agents must also implement the ability to relax this restriction
using cross-site origin controls <a href="#CORS"
rel=biblioentry>[CORS]<!--{{!CORS}}--></a>. Sites can explicitly allow
cross-site downloading of font data using the
<code>Access-Control-Allow-Origin</code> HTTP header.
<p class=issue>If an alternative mechanism to control resource loading
(such as the suggested From-Origin HTTP header) is specified, the
appropriate mechanism to relax the default same-origin restriction for
@font-face may also change. As such, this subsection should be considered
at risk for alteration if such an alternative mechanism is defined.
<h2 id=font-matching-algorithm><span class=secno>5 </span>Font matching
algorithm</h2>
<p>The algorithm below describes how fonts are associated with individual
runs of text. For each character in the run a font family is chosen and a
particular font face is selected containing a glyph for that character.
<h3 id=font-style-matching><span class=secno>5.1 </span>Matching font
styles</h3>
<p> The procedure for choosing fonts consists of iterating over the font
families determined by the font-family property, selecting a font face
with the appropriate style based on other font properties and then
determining whether a glyph exists for a given character.
<ol id=fontmatchingalg>
<li>Using the computed font property values for a given element, the user
agent starts with the first family name in the fontlist specified by the
<span class=property>‘<code class=property><a
href="#descdef-font-family">font-family</a></code>’</span> property.
<li>If the family name is unquoted and is a generic family name, the user
agent looks up the appropriate font family name to be used. User agents
may choose the generic font family to use based on the language of the
containing element or the Unicode range of the character.
<li>For other family names, the user agent attempts to find the family
name among fonts defined via @font-face rules and then among available
system fonts, matching names with a case-insensitive comparison. On
systems containing fonts with multiple localized font family names, user
agents must match any of these names independent of the underlying system
locale or platform API used. If a font family defined via @font-face
rules contains only invalid font data, it should be considered as if a
font was present but contained an empty character map; matching a
platform font with the same name must not occur in this case.
<li>If a font family match occurs, the user agent assembles the set of
font faces in that family that contain a glyph for the character. It then
narrows this matching set to a single face using other font properties in
the order given below:
<ol id=fontstylematchingalg>
<li><span class=property>‘<code class=property><a
href="#descdef-font-stretch">font-stretch</a></code>’</span> is tried
first. If the matching set contains faces with width values matching
the ‘<code class=property><a
href="#descdef-font-stretch">font-stretch</a></code>’ value, faces
with other width values are removed from the matching set. If there is
no face that exactly matches the width value the nearest width is used
instead. If the value of ‘<code class=property><a
href="#descdef-font-stretch">font-stretch</a></code>’ is ‘<code
class=property>normal</code>’ or one of the condensed values,
narrower width values are checked first, then wider values. If the
value of ‘<code class=property><a
href="#descdef-font-stretch">font-stretch</a></code>’ is one of the
expanded values, wider values are checked first, followed by narrower
values. Once the closest matching width has been determined by this
process, faces with other widths are removed from the matching set.
<li><span class=property>‘<code class=property><a
href="#descdef-font-style">font-style</a></code>’</span> is tried
next. If the value of ‘<code class=property><a
href="#descdef-font-style">font-style</a></code>’ is ‘<code
class=property>italic</code>’, italic faces are checked first, then
oblique, then normal faces. If the value is ‘<code
class=property>oblique</code>’, oblique faces are checked first, then
italic faces and then normal faces. If the value is ‘<code
class=property>normal</code>’, normal faces are checked first, then
oblique faces, then italic faces. Faces with other style values are
excluded from the matching set. User agents are permitted to
distinguish between italic and oblique faces within platform font
families but this is not required, they may treat all italic or oblique
faces as italic faces. However, within font families defined via
@font-face rules, italic and oblique faces must be distinguished using
the value of the ‘<code class=property><a
href="#descdef-font-style">font-style</a></code>’ descriptor.
<li><span class=property>‘<code class=property><a
href="#descdef-font-weight">font-weight</a></code>’</span> is matched
next, it will always reduce the matching set to a single font face. If
bolder/lighter relative weights are used, the effective weight is
calculated based on the inherited weight value, as described in the
definition of the ‘<code class=property><a
href="#descdef-font-weight">font-weight</a></code>’ property. Given
the desired weight and the weights of faces in the matching set after
the steps above, if the desired weight is available that face matches.
Otherwise, a weight is chosen using the rules below:
<ul>
<li>If the desired weight is less than 400, weights below the desired
weight are checked in descending order followed by weights above the
desired weight in ascending order until a match is found.
<li>If the desired weight is greater than 500, weights above the
desired weight are checked in ascending order followed by weights
below the desired weight in descending order until a match is found.
<li>If the desired weight is 400, 500 is checked first and then the
rule for desired weights less than 400 is used.
<li>If the desired weight is 500, 400 is checked first and then the
rule for desired weights less than 400 is used.
</ul>
<li><span class=property>‘<code class=property><a
href="#propdef-font-size">font-size</a></code>’</span> must be
matched within a UA-dependent margin of tolerance. (Typically, sizes
for scalable fonts are rounded to the nearest whole pixel, while the
tolerance for bitmapped fonts could be as large as 20%.) Further
computations, e.g., by ‘<code class=property>em</code>’ values in
other properties, are based on the <span class=property>‘<code
class=property><a
href="#propdef-font-size">font-size</a></code>’</span> value that is
used, not the one that is specified.
</ol>
<li>If no matching face exists or the matched face does not contain a
glyph for the character to be rendered, the next family name is selected
and the previous two steps repeated. If the matched font is defined via
an @font-face rule, the font resource is downloaded. If the matched font
is defined via @font-face and needs to be downloaded, the user agent can
either wait until the font is downloaded or render once with substituted
font metrics and render again once the font is downloaded.
<li>If there are no more font families to be evaluated and no matching
face has been found, then the user agent performs a <em>system font
fallback</em> procedure to find the best match for the character to be
rendered. The result of this procedure may vary across user agents.
<li>If a particular character cannot be displayed using any font, the user
agent should indicate by some means that a character is not being
displayed, displaying either a symbolic representation of the missing
glyph (e.g. using a <a
href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
Font</a>) or using the missing character glyph from a default font.
</ol>
<h3 id=char-handling-issues><span class=secno>5.2 </span>Character handling
issues</h3>
<p>The procedure above is always performed on text runs containing Unicode
characters, documents using legacy encodings are assumed to have been
transcoded before matching fonts. For fonts containing character maps for
both legacy encodings and Unicode, the contents of the legacy encoding
character map must have no effect on the results of the font matching
process.
<p>The font matching process does not assume that text runs are in either
normalized or denormalized form (see <a href="#CHARMOD-NORM"
rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
details). Layout engines often convert base character plus combining
character sequences into precomposed characters if they exist. Fonts can
generally support both ways of matching characters but variations can
occur. Authors should always tailor their choice of fonts to their
content, including whether that content contains normalized or
denormalized character streams.
<p>If a text run contains Unicode variation selectors, special handling is
required. For each character + variation selector pair, if the first font
with a glyph for the base character also contains a glyph for the variant
specified by the variation selector, user agents must display the variant
glyph instead of the default one. If the first font with a glyph for the
base character does not have a glyph for the variation selector pair, the
default glyph is displayed.
<p>If a given character is a Private-Use Area Unicode codepoint and none of
the fonts in the fontlist contain a glyph for that codepoint, user agents
must display some form of missing glyph symbol for that character rather
than attempting system font fallback for that codepoint. When matching the
replacement character U+FFFD, user agents may skip the font matching
process and immediately display some form of missing glyph symbol, they
are not required to display the glyph from the font that would be selected
by the font matching process.
<p>In general, the fonts for a given family will all have the same or
similar character maps. The process outlined here is designed to handle
even font families containing faces with widely variant character maps.
However, authors are cautioned that the use of such families can lead to
unexpected results. A special character only available in the condensed
italic face of a family may still be used even when font properties imply
a bold expanded face should be used instead.
<p>Optimizations of this process are allowed provided that an
implementation behaves as if the algorithm had been followed exactly.
Matching occurs in a well-defined order to insure that the results are as
consistent as possible across user agents, given an identical set of
available fonts and rendering technology.
<p class=issue>How to match grapheme clusters needs to be specified
explicitly.
<h3 id=font-matching-changes><span class=secno>5.3 </span>Font matching
changes since CSS 2.1</h3>
<p>The algorithm above is different from CSS 2.1 in a number of key places.
These changes were made to better reflect actual font matching behavior
across user agent implementations.
<p>Differences compared to the font matching algorithm in CSS 2.1:
<ul>
<li>The algorithm includes font-stretch matching.
<li>All possible font-style matching scenarios are delineated.
<li>Small-caps fonts are not matched as part of the font matching process,
they are now handled via font features.
<li>Unicode variation selector matching is required.
</ul>
<!--
<h3>Examples of font matching</h3>
<p>Simple to complex examples:</p>
<div class="example">
<p>bold italic</p>
</div>
<div class="example">
<p>italic (synthesized)</p>
</div>
<div class="example">
<p>specific weights</p>
</div>
<div class="example">
<p>bolder/lighter</p>
</div>
<div class="example">
<p>bolder (synthesized)</p>
</div>
<div class="example">
<p>condensed</p>
</div>
<div class="example">
<p>run of text containing diacritics</p>
</div>
<div class="example">
<p>run of text containing mixture of Japanese/English</p>
</div>
<div class="example">
<p>simple downloaded font</p>
</div>
<div class="example">
<p>font-face with local/url combination</p>
</div>
-->
<div class=example>
<p>It's useful to note that the CSS selector syntax may be used to create
language-sensitive typography. For example, some Chinese and Japanese
characters are unified to have the same Unicode code point, although the
abstract glyphs are not the same in the two languages.
<pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
*:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
</pre>
<p>This selects any element that has the given language - Japanese or
Traditional Chinese - and uses the appropriate font.
</div>
<h2 id=font-rend-props><span class=secno>6 </span>Font feature properties</h2>
<p>Modern font technologies support a variety of advanced typographic and
language-specific font features. Using these features, a single font can
provide glyphs for a wide range of ligatures, contextual and stylistic
alternates, tabular and old-style figures, small capitals, automatic
fractions, swashes, and alternates specific to a given language. To allow
authors control over these font capabilities, the font-variant property
has been expanded for CSS3, it now functions as a shorthand for a set of
properties that provide control over stylistic font features.
<h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
selection and positioning</h3>
<p>Simple fonts used for displaying Latin text use a very basic processing
model, fonts contain a character map which maps a given character to a
glyph for that character. Glyphs for subsequent characters are simply
placed next in line along a run of text. Font formats such as OpenType and
AAT (Apple Advanced Typography) use a richer processing model, the glyph
for a given character can be chosen and positioned not just based on a
single character, but also based on surrounding characters along with the
language, script, and features enabled for the text. Font features may be
required for specific scripts, or recommended as enabled by default or
they may be stylistic features meant to be used under author control.
<p>For a good visual overview of these features, see the <a
href="#OPENTYPE-FONT-GUIDE"
rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
For a detailed description of glyph processing for OpenType fonts, see <a
href="#WINDOWS-GLYPH-PROC"
rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
<p>The subproperties of font-variant listed below are used to control these
stylistic font features; they do not control features that are required
for displaying certain scripts, such as the OpenType features used when
displaying Arabic or Indic language text. They affect glyph selection and
positioning, they do not affect font selection as described in the font
matching section (except in cases required for compatibility with CSS
2.1).
<p>To assure consistent behavior across user agents, the equivalent
OpenType property settings are listed for individual properties and must
be considered normative. When using other font formats these should be
used as a guideline to map CSS font feature property values to specific
font features.
<p class=issue>The complete set of features on by default is not completely
specified in OpenType documentation. Should these be listed in a normative
appendix or should a more complete list be requested from those
controlling the OpenType specification?</p>
<!--
<p>For fonts defined via @font-face rules, the ‘<code class=property>font-variant</code>’
descriptor of the @font-face rule described below can be used to
specify font features that only apply to a given font.
Features not supported by any of the properties defined here
can be enabled using the
‘<code class=property>font-feature-settings</code>’ descriptor of the @font-face rule allows the
use of infrequently used font features. Authors are encouraged to use
‘<code class=property>font-variant</code>’ properties whenever possible.</p>
All of these properties assume that fonts define a given set of
default rendering styles; if a specific font feature is not explicitly
enabled or disabled the default rendering style is used. For each of
these properties, the value ‘<code class=property>normal</code>’ implies using the font
defaults.</p>
<p>Like other font properties, font feature properties apply independent
of the font specified. In some cases, font feature settings are
font-specific, such as when specifying swash characters or stylistic
alternates. In these situations, the ‘<code class=property>font-variant</code>’ descriptor of the
@font-face rule described below can be used to specify font features
that only apply to a given font and not to other fonts when fallback
occurs. For features not supported by any of the properties defined
here, the ‘<code class=property>font-feature-settings</code>’ descriptor of the @font-face rule allows
the use of infrequently used font features. Authors are encouraged
to use ‘<code class=property>font-variant</code>’ properties whenever possible.</p>
<p>For features not supported by subproperties of font-variant defined
below, the ‘<code class=property>font-feature-settings</code>’ descriptor of the @font-face rule allows
the use of infrequently used font features. Authors are encouraged
to use ‘<code class=property>font-variant</code>’ properties whenever possible.</p>
-->
<h3 id=language-specific-support><span class=secno>6.2
</span>Language-specific display</h3>
<p>OpenType also supports language-specific glyph selection and
positioning, so that text can be displayed correctly in cases where the
language dictates a specific display behavior. Languages often share a
common script but the shape of certain letters may vary across those
languages, such as the variations in certain Cyrillic letters used in
Russian and Bulgarian text. In Latin text, it's common to render "fi" with
an explicit fi-ligature that lacks a dot on the "i". However, in languages
such as Turkish which uses both a dotted-i and a dotless-i, it's important
to not use this ligature or use a specialized version that contains a dot
over the "i". The example below shows language-specific variations based
on stylistic traditions found in Spanish, Italian and French orthography:
<div class=featex><img alt="language specific forms, spanish"
src=locl-1.png></div>
<div class=featex><img alt="language specific forms, italian"
src=locl-2.png></div>
<div class=featex><img alt="language specific forms, french"
src=locl-3.png></div>
<p>Users agents are required to infer the OpenType language system from the
value of the ‘<code class=property>lang</code>’ attribute and use that
when selecting and positioning glyphs using an OpenType font. If the
‘<code class=property>lang</code>’ attribute is not defined, the
default OpenType language system must be used.
<p>In some cases it may be necessary to explicitly declare the OpenType
language to be used, for example when displaying text in a given language
that uses the typographic conventions of another language, or when the
font does not explicitly support a given language but supports a language
that shares common typographic conventions. The ‘<code class=property><a
href="#propdef-font-language-override">font-language-override</a></code>’
property is used for this purpose.
<p class=issue>Should user agents be allowed to infer the Opentype language
or simply use only the default language system?</p>
<!-- prop: font-kerning -->
<h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
href="#propdef-font-kerning">font-kerning</a> property</h3>
<table class=propdef id=namefont-kerning>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-kerning>font-kerning</dfn>
<tr>
<td>Value:
<td>auto | normal | none
<tr>
<td>Initial:
<td>auto
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>Kerning is the contextual adjustment of inter-glyph spacing. This
property controls metric kerning, kerning that utilizes adjustment data
contained in the font. The value ‘<code class=property>normal</code>’
implies that kerning is applied while the value ‘<code
class=property>none</code>’ implies that kerning is not applied when
rendering text. If the value is ‘<code class=property>auto</code>’, a
user agent is free to choose whether kerning is enabled or not by default
and to vary that default based on the underlying text script.
<p>For fonts that do not include kerning data this property will have no
visible effect. When rendering with OpenType fonts, the <a
href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
specification suggests that kerning be enabled by default. When kerning is
enabled, the OpenType <code>kern</code> feature is enabled. User agents
must also support fonts that only support kerning via data contained in a
‘<code class=property>kern</code>’ font table, as detailed in the
OpenType specification. Authors may prefer to disable kerning in
situations where performance is more important that precise appearance. If
the ‘<code class=property>letter-spacing</code>’ property is defined,
kerning adjustments are considered part of the default spacing, letter
spacing adjustments are made after kerning has been applied.</p>
<!-- prop: font-variant-position -->
<h3 id=font-variant-position-prop><span class=secno>6.4 </span>Subscript,
superscript and ordinal forms: the <a
href="#propdef-font-variant-position">font-variant-position</a> property</h3>
<table class=propdef id=namefont-variant-position>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
<tr>
<td>Value:
<td>normal | sub | super | ordinal
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p class=issue>The name for this feature has been a point of contention,
this name is a placeholder until the final name is resolved.
<p>This property controls the selection of alternate glyphs for use as
subscripts, superscripts and ordinals. These alternate glyphs of reduced
size are positioned within the same em-box as the default glyph and
explicitly designed to match the surrounding text and make the them more
readable without affecting the linebox.
<div class=figure><img alt="comparison between real subscript glyphs and
synthesized ones" src=realsubscripts.png>
<p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
(bottom)
</div>
<p>The values ‘<code class=property>sub</code>’, ‘<code
class=property>super</code>’, and ‘<code
class=property>ordinal</code>’ imply the appropriate variant glyph is
displayed when available in the font (OpenType features: <code>subs, supr,
ordn</code>). Because of the semantic nature of subscripts and
superscripts, when the value is either ‘<code
class=property>sub</code>’ or ‘<code class=property>super</code>’
and a variant glyph is not available, a simulated glyph is synthesized
using a reduced form of the default glyph. If the value is ‘<code
class=property>ordinal</code>’ and a variant glyph is not available, the
normal glyph is used, no attempt is made to synthesize one. A value of
‘<code class=property>normal</code>’ implies use of the default glyph
at normal size.
<p>In the case of OpenType fonts that lack subscript or superscript glyphs
for a given character, to calculate the size and offset of the synthesized
substitutes user agents must use the appropriate subscript and superscript
metrics specified in the selected font's <a
href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
table</a> <a href="#OPENTYPE"
rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
<p>In the past, user agents have used font-size and vertical-align to
simulate subscripts and superscripts for the <code>sub</code> and
<code>sup</code> elements. To allow a backwards compatible way of defining
subscripts and superscripts, it is recommended that authors use
conditional rules <a href="#CSS3-CONDITIONAL"
rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
older user agents will still render these correctly.
<p>Note that because this property is not cumulative, it's not suitable for
nested subscripts or superscripts. Due to this limitation,
font-variant-position is not recommended for use in user agent
stylesheets.
<p class=issue>It would be nice to define this in a way such that it would
work with nested subscripts or superscripts which would allow it to be
used in user agent stylesheets. But one of the goals for this is to allow
simple subscripts and superscripts to be displayed without affecting the
line box. To achieve both appears to be a very hairy problem. One <a
href="http://lists.w3.org/Archives/Public/www-style/2011Apr/0391.html">proposal</a>
is to conditionalize how the font-size and vertical-align properties are
used based on whether subscript or superscript glyphs are available.
<p class=issue>Fonts often include default values for subscript/superscript
metrics. As a result, a mixture of designed glyphs and simulated glyphs
may not display correctly, the baseline will appear to bounce between
sequences to designed and simulated glyphs.
<div class=example>
<p>A typical user agent default style for the <code>sub</code> element:</p>
<pre>sub {
vertical-align: sub;
font-size: smaller;
line-height: normal;
}
</pre>
<p>Using font-variant-position to specify typographic subscripts in a way
that will still show subscripts in older user agents:</p>
<pre>@supports ( font-variant-position: sub ) {
sub {
vertical-align: inherit;
font-size: 100%;
line-height: inherit;
font-variant-position: sub;
}
}
</pre>
<p>User agents that support the ‘<code class=property><a
href="#propdef-font-variant-position">font-variant-position</a></code>’
property will select a subscript variant glyph and render this without
adjusting the baseline or font-size. Older user agents will ignore the
‘<code class=property><a
href="#propdef-font-variant-position">font-variant-position</a></code>’
property definition and use the standard defaults for subscripts.</p>
</div>
<!-- prop: font-variant-ligatures -->
<h3 id=font-variant-ligatures-prop><span class=secno>6.5 </span>Ligatures:
the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
property</h3>
<table class=propdef id=namefont-variant-ligatures>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
<tr>
<td>Value:
<td>normal | inherit | [ <common-lig-values> ||
<discretionary-lig-values> || <historical-lig-values> ]
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>Specifies control over which ligatures are enabled or disabled. A value
of ‘<code class=property>normal</code>’ implies that the defaults set
by the font are used.
<pre
class=prod><dfn id=ltcommon-lig-values><var><common-lig-values></var></dfn> = [ common-ligatures | no-common-ligatures ]</pre>
<pre
class=prod><dfn id=ltdiscretionary-lig-values><var><discretionary-lig-values></var></dfn> = [ discretionary-ligatures | no-discretionary-ligatures ]</pre>
<pre
class=prod><dfn id=lthistorical-lig-values><var><historical-lig-values></var></dfn> = [ historical-ligatures | no-historical-ligatures ]</pre>
<p>Individual values have the following meanings:
<dl>
<dt><dfn id=common-ligatures>common-ligatures</dfn>
<dd>Enables display of common ligatures (OpenType feature:
<code>liga</code>). For OpenType fonts, common ligatures are enabled by
default.
</dl>
<div class=featex><img alt="common ligature example" src=liga.png></div>
<dl>
<dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
<dd>Disables display of common ligatures (OpenType feature:
<code>liga</code>).
<dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
<dd>Enables display of discretionary ligatures (OpenType feature:
<code>dlig</code>). Which ligatures are discretionary, or optional, is
decided by the type designer so authors will need to refer to the
documentation of a given font to understand which ligatures are
considered discretionary.
</dl>
<div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
<dl>
<dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
<dd>Disables display of discretionary ligatures (OpenType feature:
<code>dlig</code>).
<dt><dfn id=historical-ligatures>historical-ligatures</dfn>
<dd>Enables display of historical ligatures (OpenType feature:
<code>hlig</code>).
</dl>
<div class=featex><img alt="historical ligature example" src=hlig.png></div>
<dl>
<dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
<dd>Disables display of historical ligatures (OpenType feature:
<code>hlig</code>).
</dl>
<p>Required ligatures, needed for correctly rendering complex scripts, are
not affected by the settings above.</p>
<!-- prop: font-variant-caps -->
<h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
<table class=propdef id=namefont-variant-caps>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
<tr>
<td>Value:
<td>normal | inherit | <caps-value>
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>Specifies control over capitalized forms.
<pre
class=prod><dfn id=ltcaps-valuegt><var><caps-value></var></dfn> = small-caps | all-small-caps | petite-caps | all-petite-caps | titling-caps | unicase</pre>
<p>Individual values have the following meanings:
<dl>
<dt><dfn id=small-caps>small-caps</dfn>
<dd>Enables display of small capitals (OpenType feature:
<code>smcp</code>). Small-caps glyphs typically use the form of uppercase
letters but are reduced to the size of lowercase letters.
</dl>
<div class=featex><img alt="small-caps example" src=smcp.png></div>
<dl>
<dt><dfn id=all-small-caps>all-small-caps</dfn>
<dd>Enables display of small capitals for both upper and lowercase letters
(OpenType features: <code>c2sc, smcp</code>).
<dt><dfn id=petite-caps>petite-caps</dfn>
<dd>Enables display of petite capitals (OpenType feature:
<code>pcap</code>).
<dt><dfn id=all-petite-caps>all-petite-caps</dfn>
<dd>Enables display of petite capitals for both upper and lowercase
letters (OpenType features: <code>c2pc, pcap</code>).
<dt><dfn id=titling-caps>titling-caps</dfn>
<dd>Enables display of titling capitals (OpenType feature:
<code>titl</code>). Uppercase letter glyphs are often designed for use
with lowercase letters. When used in all uppercase titling sequences they
can appear too strong. Titling capitals are designed specifically for
this situation.
<dt><dfn id=unicase>unicase</dfn>
<dd>Enables display of mixture of small capitals for uppercase letters
with normal lowercase letters (OpenType feature: <code>unic</code>).
</dl>
<p>For backwards compatibility with CSS 2.1, if ‘<code class=property><a
href="#small-caps">small-caps</a></code>’ or ‘<code class=property><a
href="#all-small-caps">all-small-caps</a></code>’ is specified but
small-caps glyphs are not available for a given font, user agents should
simulate a small-caps font, for example by taking a normal font and
replacing the lowercase letters by scaled uppercase characters (and also
uppercase letters in the case of ‘<code class=property><a
href="#all-small-caps">all-small-caps</a></code>’). As a last resort,
unscaled uppercase letter glyphs in a normal font may replace glyphs in a
small-caps font so that the text appears in all uppercase letters. If
either ‘<code class=property><a
href="#petite-caps">petite-caps</a></code>’ or ‘<code
class=property><a href="#all-petite-caps">all-petite-caps</a></code>’ is
specified for a font that doesn't support these features, the property
behaves as if ‘<code class=property><a
href="#small-caps">small-caps</a></code>’ or ‘<code class=property><a
href="#all-small-caps">all-small-caps</a></code>’, respectively, had
been specified. If ‘<code class=property><a
href="#titling-caps">titling-caps</a></code>’ is specified with a font
that does not support these features, this property has no visible effect.
For scripts that lack uppercase and lowercase letters, ‘<code
class=property><a href="#small-caps">small-caps</a></code>’, ‘<code
class=property><a href="#all-small-caps">all-small-caps</a></code>’,
‘<code class=property><a href="#petite-caps">petite-caps</a></code>’,
‘<code class=property><a
href="#all-petite-caps">all-petite-caps</a></code>’ and ‘<code
class=property><a href="#unicase">unicase</a></code>’ have no visible
effect.
<div class=example>
<p>Quotes rendered italicised, with small-caps on the first line:</p>
<pre>blockquote { font-style: italic; }
blockquote:first-line { font-variant: small-caps; }
<blockquote><a href="http://lists.w3.org/Archives/Public/www-style/2009Dec/0036.html" style="text-decoration: none">I'll be honor-bound to slap them like a haddock.</a></blockquote>
</pre>
</div>
<p>Insofar as this property causes text to be transformed to uppercase, the
same considerations as for <span class=property>‘<code
class=property>text-transform</code>’</span> apply.</p>
<!-- prop: font-variant-numeric -->
<h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
formatting: the <a
href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
<table class=propdef id=namefont-variant-numeric>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
<tr>
<td>Value:
<td>normal | inherit | [ <numeric-figure-values> ||
<numeric-spacing-values> || <numeric-fraction-values> ||
slashed-zero ]
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>Specifies control over numerical forms.
<pre
class=prod><dfn id=ltnumeric-figure-valuesgt><var><numeric-figure-values></var></dfn> = [ lining-nums | oldstyle-nums ]</pre>
<pre
class=prod><dfn id=ltnumeric-spacing-valuesgt><var><numeric-spacing-values></var></dfn> = [ proportional-nums | tabular-nums ]</pre>
<pre
class=prod><dfn id=ltnumeric-fraction-valuesgt><var><numeric-fraction-values></var></dfn> = [ diagonal-fractions | stacked-fractions ]</pre>
<p>Individual values have the following meanings:
<dl>
<dt><dfn id=lining-nums>lining-nums</dfn>
<dd>Enables display of lining numerals (OpenType feature:
<code>lnum</code>).
<dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
<dd>Enables display of old-style numerals (OpenType feature:
<code>onum</code>).
<dt><dfn id=proportional-nums>proportional-nums</dfn>
<dd>Enables display of proportional numerals (OpenType feature:
<code>pnum</code>).
<dt><dfn id=tabular-nums>tabular-nums</dfn>
<dd>Enables display of tabular numerals (OpenType feature:
<code>tnum</code>).
</dl>
<p>The example below shows how these different properties can be combined
to influence the rendering of tabular data with fonts that support these
features. Within normal paragraph text, proportional numbers are used
while tabular numbers are used so that columns of numbers line up
properly:
<div class=figure style="padding: 0; margin: auto;"><img alt="combining
number styles" src=numberstyles.png>
<p class=caption>Using number styles
</div>
<dl>
<dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
<dd>Enables display of lining diagonal fractions (OpenType feature:
<code>frac</code>).
</dl>
<div class=featex><img alt="diagonal fraction example" src=frac.png></div>
<dl>
<dt><dfn id=stacked-fractions>stacked-fractions</dfn>
<dd>Enables display of lining stacked fractions (OpenType feature:
<code>afrc</code>).
</dl>
<div class=featex><img alt="stacked fraction example" src=afrc.png></div>
<dl>
<dt><dfn id=slashed-zero>slashed-zero</dfn>
<dd>Enables display of slashed zeros (OpenType feature:
<code>zero</code>).
</dl>
<div class=featex><img alt="slashed zero example" src=zero.png></div>
<div class=example id=steak-marinade>
<p>A simple flank steak marinade recipe, rendered with automatic fractions
and old-style numerals:</p>
<pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
<h4>Steak marinade:</h4>
<ul>
<li><span class="amount">2</span> tbsp olive oil</li>
<li><span class="amount">1</span> tbsp lemon juice</li>
<li><span class="amount">1</span> tbsp soy sauce</li>
<li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
<li><span class="amount">2 1/2</span> tsp italian seasoning</li>
<li>Salt &amp; pepper</li>
</ul>
<p>Mix the meat with the marinade and let it sit covered in the refrigerator for a few hours or overnight.</p>
</pre>
</div>
<!-- prop: font-variant-alternates -->
<h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
and swashes: the <a
href="#propdef-font-variant-alternates">font-variant-alternates</a>
property</h3>
<table class=propdef id=namefont-variant-alternates>
<tbody>
<tr>
<td>Name:
<td><dfn
id=propdef-font-variant-alternates>font-variant-alternates</dfn>
<tr>
<td>Value:
<td>normal | inherit | [ <contextual-alt-values> ||
stylistic(<feature-value-name>) || historical-forms ||
styleset(<feature-value-name> [, <feature-value-name>]*) ||
character-variant(<feature-value-name>
[,<feature-value-name>]*) || swash(<feature-value-name>) ||
ornaments(<feature-value-name>) ||
annotation(<feature-value-name>) || ruby ]
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<pre
class=prod><dfn id=ltcontextual-alt-valuesgt><var><contextual-alt-values></var></dfn> = [ contextual | no-contextual ]</pre>
<p>For any given character, fonts can provide a variety of alternate glyphs
in addition to the default glyph for that character. This property
provides control over the selection of these alternate glyphs.
<p>In cases where multiple alternates are possible, authors define a
<code><a
href="#ltfeature-value-namegt"><feature-value-name></a></code> using
the <code>@font-feature-values</code> rule described below to indicate the
specific alternate to be used. The nature of these alternates is font
specific, so the rule defines values for a specific font family or set of
families. When a particular value has not been defined for a given family,
the named value is treated as if the feature had omitted from the style
rule. If a given value is outside the range supported by a given font, the
value is ignored. These values never apply to generic font families, nor
to families selected as part of system font fallback. Values that behave
this way are marked as <em>font specific</em>.
<p>Individual values have the following meanings:
<dl>
<dt><dfn
id=stylisticltfeature-value-namegt>stylistic(<feature-value-name>)</dfn>
<dd>Enables display of stylistic alternates (<em>font specific</em>,
OpenType feature: <code>salt <feature-value-name></code>).
</dl>
<div class=featex><img alt="stylistic alternate example" src=salt.png></div>
<dl>
<dt><dfn id=contextual>contextual</dfn>
<dd>Enables display of contextual alternates (OpenType feature:
<code>calt, clig</code>).
</dl>
<div class=featex><img alt="contextual alternate example" src=calt.png></div>
<dl>
<dt><dfn id=no-contextual>no-contextual</dfn>
<dd>Disables display of contextual alternates (OpenType feature:
<code>calt, clig</code>).
<dt><dfn id=historical-forms>historical-forms</dfn>
<dd>Enables display of historical forms (OpenType feature:
<code>hist</code>).
</dl>
<div class=featex><img alt="historical form example" src=hist.png></div>
<dl>
<dt><dfn
id=stylesetltfeature-value-namegt>styleset(<feature-value-name>
[,<feature-value-name>]*)</dfn>
<dd>Enables display with stylistic sets (<em>font specific</em>, OpenType
feature: <code>ss<feature-index></code> OpenType currently defines
<code>ss01</code> through <code>ss20</code>).
</dl>
<div class=featex><img alt="styleset example" src=ssnn.png></div>
<dl>
<dt><dfn
id=character-variantltfeature-value-namegt>character-variant(<feature-value-name>
[,<feature-value-name>]*)</dfn>
<dd>Enables display of specific character variants (<em>font
specific</em>, OpenType feature: <code>cv<feature-index></code>
OpenType currently defines <code>cv01</code> through <code>cv99</code>).
<dt><dfn
id=swashltfeature-value-namegt>swash(<feature-value-name>)</dfn>
<dd>Enables display of swash glyphs (<em>font specific</em>, OpenType
feature: <code>swsh <feature-index>, cswh
<feature-index></code>).
</dl>
<div class=featex><img alt="swash example" src=swsh.png></div>
<dl>
<dt><dfn
id=ornamentsltfeature-value-namegt>ornaments(<feature-value-name>)</dfn>
<dd>Enables replacement of default glyphs with ornaments, if provided in
the font (<em>font specific</em>, OpenType feature: <code>ornm
<feature-index></code>). Some fonts may offer ornament glyphs as
alternates for a wide collection of characters; however, displaying
arbitrary characters (e.g., alphanumerics) as ornaments is poor practice
as it distorts the semantics of the data. Font designers are encouraged
to encode all ornaments (except those explicitly encoded in the Unicode
Dingbats blocks, etc.) as alternates for the bullet character (U+2022) to
allow authors to select the desired glyph using
<feature-value-name>.
</dl>
<div class=featex><img alt="ornaments example" src=ornm.png></div>
<dl>
<dt><dfn
id=annotationltfeature-value-namegt>annotation(<feature-value-name>)</dfn>
<dd>Enables display of alternate annotation forms (<em>font specific</em>,
OpenType feature: <code>nalt <feature-index></code>).
</dl>
<div class=featex><img alt="alternate annotation form example"
src=nalt.png></div>
<dl>
<dt><dfn id=ruby>ruby</dfn>
<dd>Enables display of ruby variant glyphs (OpenType feature:
<code>ruby</code>). This value only selects a glyph for use in ruby text,
it does not affect font scaling. The red ruby text below is shown with
default glyphs (top) and with ruby variant glyphs (bottom). Note the
slight difference in stroke thickness.
</dl>
<div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
<h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
specific alternates: the @font-feature-values rule</h3>
<p>Several of the possible values of ‘<code class=property><a
href="#propdef-font-variant-alternates">font-variant-alternates</a></code>’
listed above are labeled as "font specific". For these features fonts may
define not just a single glyph but a set of alternate glyphs with an index
to select a given alternate. Since these are font family specific, the
@font-feature-values rule is used to define named-values for these indices
for a given family.
<p>In the case of the swash Q in the example shown above, the swash could
be specified using these style rules:
<pre>
@font-feature-values Jupiter Sans {
@swash delicate 1, flowing 2;
}
h2 { font-family: Jupiter Sans, sans-serif; }
/* show the second swash variant in h2 headings */
h2:first-letter { font-variant-alternates: swash(flowing); }
<h2>Quick</h2></pre>
<p>When Jupiter Sans is present, the second alternate swash alternate will
be displayed. When not present, no swash character will be shown, since
the specific named-value "flowing" is only defined for the Jupiter Sans
family. The @-mark indicates the name of the property value for which a
named-value can be used. The name "flowing" is chosen by the author.
<p>The syntax of the @font-feature-values rule is defined as:
<pre>
@font-feature-values <font-family> [, <font-family>]* {
<font-variant-value-definition>;
<font-variant-value-definition>;
.
.
}
</pre>
<p>where:
<pre
class=prod><dfn id=ltfont-variant-value-definitiongt><var><font-variant-value-definition></var></dfn> = @<font-variant-value> <feature-value-list> [, <feature-value-list>]*</pre>
<pre
class=prod><dfn id=ltfont-familygt><var><font-family></var></dfn> = font family name, quoted or unquoted, using the same quoting rules that apply within style rules</pre>
<pre
class=prod><dfn id=ltfont-variant-valuegt><var><font-variant-value></var></dfn> = the name of one of the font-specific font-variant values (e.g. swash, styleset, annotation)</pre>
<pre
class=prod><dfn id=ltfeature-value-listgt><var><feature-value-list></var></dfn> = <feature-value-name> <feature-index>+</pre>
<pre
class=prod><dfn id=ltfeature-value-namegt><var><feature-value-name></var></dfn> = a user-defined identifier used to describe the index</pre>
<pre
class=prod><dfn id=ltfeature-indexgt><var><feature-index></var></dfn> = an integer value greater than 0 specific to a given font or set of fonts</pre>
<p>These @font-feature-values rules can appear anywhere within a stylesheet
and are exposed bidirectionally across @import boundaries. If multiple
@font-feature-values rules are defined for a given family, the resulting
values defined are the union of these rules. This allows a set of
named-values to be defined for a given font family globally for a site and
specific additions made per-page. If the same <feature-value-name>
is defined mulitple times for a given font-variant value, the last defined
value is used.
<pre>
site.css:
@font-feature-values Mercury Serif {
@styleset stacked-g 3, stacked-a 4; /* "two-storey" versions of g, a */
}
page.css:
@font-feature-values Mercury Serif {
@styleset geometric-m 7; /* alternate version of m */
}
body {
font-family: Mercury Serif, serif;
/* enable both the use of stacked g and alternate m */
font-variant-alternates: styleset(stacked-g, geometric-m);
}</pre>
<p>Only named font families are allowed for <font-family>, rules
defined for generic and system fonts must be ignored. However, if a user
agent defines a generic font to be a specific named font (e.g. Helvetica),
the settings associated with that family name will be used.
<p>For font-variant-value, only font-specific value names supported by the
‘<code class=property><a
href="#propdef-font-variant">font-variant</a></code>’ property are
recognized, definitions for other value names are a syntax error and
ignored. Each value that is font specific is clearly marked as such.
Feature value names follow the rules of CSS identifiers and are unique
only for a given set of font families and font variant value; the same
identifier used with a different font variant value is treated as a
distinct value.
<p>Using a commonly named value allows authors to use a single style rule
to cover a set of fonts for which the underlying selector is different for
each font. If either font in the example below is found, a circled number
glyph will be used:
<pre>@font-feature-values Taisho Gothic {
@annotation boxed 1, circled 4;
}
@font-feature-values Otaru Kisa {
@annotation circled 1, black-boxed 3;
}
h3.title {
/* circled form defined for both fonts */
font-family: Taisho Gothic, Otaru Kisa;
font-variant: annotation(circled);
}</pre>
<p>Most font-specific font-variant values take a single value (e.g. swash).
If multiple values are assigned to a given name a syntax error occurs and
the entire <font-variant-value-definition> is ignored. For the
styleset value, multiple values can be assigned to a given name. Multiple
values indicate the style sets to be enabled. Values between 1 and 20
enable OpenType features ‘<code class=css>ss01</code>’ through
‘<code class=css>ss20</code>’. Values greater than 20 are ignored.
<pre>@font-feature-values Mars Serif {
@styleset alt-g 1, /* implies ss01 = 1 */
curly-quotes 3, /* implies ss03 = 1 */
code 4 5; /* implies ss04 = 1, ss05 = 1 */
}
p.codeblock {
/* implies ss03 = 1, ss04 = 1, ss05 = 1 */
font-variant-alternates: styleset(curly-quotes, code);
}</pre>
<p>For character-variant, a single value between 1 and 99 indicates the
enabling of OpenType feature ‘<code class=css>cv01</code>’ through
‘<code class=css>cv99</code>’. Values greater than 99 are ignored.
When two values are listed, the first value indicates the feature used and
the second the value passed for that feature. Values beyond the first two
are ignored.
<pre>@font-feature-values MM Greek {
@character-variant alpha-2 1 2; /* implies cv01 = 2 */
@character-variant beta-3 2 3; /* implies cv02 = 3 */
@character-variant gamma 12; /* implies cv12 = 1 */
@character-variant zeta 20 3 2; /* implies cv20 = 3, '2' is ignored */
@character-variant silly 105; /* >99, ignored */
@character-variant dumb 323 3; /* >99, ignored */
}
#title {
/* use the third alternate beta, first alternate gamma */
font-variant-alternates: character-variant(beta-3, gamma);
}</pre>
<p>See <a href="#font-feature-values-DOM">Appendix C</a> for a description
of the interfaces used to modify these rules via the CSS Object Model.
<div class=figure><img alt="Matching text on Byzantine seals using
character variants" src=byzantineseal.png>
<p class=caption>Byzantine seal text displayed with character variants
</div>
<div class=example>
<p>In the figure above, the text in red is rendered using a font
containing character variants that mimic the character forms found on a
Byzantine seal from the 8th century A.D. Two lines below is the same text
displayed in a font without variants. Note the two variants for U and N
used on the seal.</p>
<pre>@font-feature-values Athena Ruby {
@character-variant
leo-B 2 1, leo-M 13 3,
leo-alt-N 14 1, leo-N 14 2,
leo-T 20 1,
leo-U 21 2, leo-alt-U 21 4;
}
p {
font-variant: discretionary-ligatures, character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
}
span.alt-N {
font-variant-alternates: character-variant(leo-alt-N);
}
span.alt-U {
font-variant-alternates: character-variant(leo-alt-U);
}
<p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
<p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
</pre>
</div>
<h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
Asian text rendering: the <a
href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
property</h3>
<table class=propdef id=namefont-variant-east-asian>
<tbody>
<tr>
<td>Name:
<td><dfn
id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
<tr>
<td>Value:
<td>normal | inherit | [ <east-asian-variant-values> ||
<east-asian-width-values> ]
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>Allows control of glyph substitute and positioning in East Asian text.
In cases where multiple alternates are possible, an integer is included to
indicate the index of the alternate to be used. Omitting the integer
indicates the first alternate.
<pre
class=prod><dfn id=lteast-asian-variant-valuesgt><var><east-asian-variant-values></var></dfn> = [ jis78 | jis83 | jis90 | jis04 | simplified | traditional ]</pre>
<pre
class=prod><dfn id=lteast-asian-width-valuesgt><var><east-asian-width-values></var></dfn> = [ full-width | proportional-width ]</pre>
<p>Individual values have the following meanings:
<dl>
<dt><dfn id=jis78>jis78</dfn>
<dd>Enables rendering of JIS78 forms (OpenType feature:
<code>jp78</code>).
</dl>
<div class=featex><img alt="JIS78 form example" src=jp78.png></div>
<dl>
<dt><dfn id=jis83>jis83</dfn>
<dd>Enables rendering of JIS83 forms (OpenType feature:
<code>jp83</code>).
<dt><dfn id=jis90>jis90</dfn>
<dd>Enables rendering of JIS90 forms (OpenType feature:
<code>jp90</code>).
<dt><dfn id=jis04>jis04</dfn>
<dd>Enables rendering of JIS2004 forms (OpenType feature:
<code>jp04</code>).
<dt><dfn id=simplified>simplified</dfn>
<dd>Enables rendering of simplified forms (OpenType feature:
<code>smpl</code>).
<dt><dfn id=traditional>traditional</dfn>
<dd>Enables rendering of traditional forms (OpenType feature:
<code>trad</code>).
</dl>
<div class=featex><img alt="tradtional form example" src=trad.png></div>
<dl>
<dt><dfn id=full-width>full-width</dfn>
<dd>Enables rendering of full-width variants (OpenType feature:
<code>fwid</code>).
<dt><dfn id=proportional-width>proportional-width</dfn>
<dd>Enables rendering of proportionally-spaced variants (OpenType feature:
<code>pwid</code>).
</dl>
<div class=featex><img alt="proportionally spaced Japanese example"
src=pwid.png></div>
<h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
for font rendering: the <a href="#propdef-font-variant">font-variant</a>
property</h3>
<table class=propdef id=namefont-variant>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-variant>font-variant</dfn>
<tr>
<td>Value:
<td>normal | inherit | [ <common-lig-values> ||
<discretionary-lig-values> || <historical-lig-values> ||
<contextual-alt-values> || stylistic(<feature-value-name>)
|| historical-forms || styleset(<feature-value-name> [,
<feature-value-name>]*) ||
character-variant(<feature-value-name>
[,<feature-value-name>]*) || swash(<feature-value-name>) ||
ornaments(<feature-value-name>) ||
annotation(<feature-value-name>) || ruby || <caps-value> ||
<numeric-figure-values> || <numeric-spacing-values> ||
<numeric-fraction-values> || slashed-zero ||
<east-asian-variant-values> || <east-asian-width-values> ]
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>The value ‘<code class=property>normal</code>’ resets all other font
feature properties to normal and font defaults are used when rendering
text. Like other shorthands, using ‘<code class=property><a
href="#propdef-font-variant">font-variant</a></code>’ resets all font
feature properties to their initial values. It does not reset the values
of either ‘<code class=property><a
href="#propdef-font-language-override">font-language-override</a></code>’
or ‘<code class=property><a
href="#propdef-font-feature-settings">font-feature-settings</a></code>’.
<h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
font feature settings control: the <a
href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
<table class=propdef id=namefont-feature-settings>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-feature-settings>font-feature-settings</dfn>
<tr>
<td>Value:
<td>normal | <feature-tag-value> [, <feature-tag-value>]*
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>This property provides low-level control over OpenType font features. It
is intended as a way of providing access to font features that are not
widely used but are needed for a particular use case. A value of ‘<code
class=property>normal</code>’ means that no change in glyph selection or
positioning occurs due to this property.
<p>
<pre>/* enable small caps and use second swash alternate */
font-feature-settings: "smcp", "swsh" 2;</pre>
<p>Feature tag values have the following syntax:
<pre
class=prod><dfn id=ltfeature-tag-valuegt><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
<p>The <string> is a case-sensitive OpenType feature tag. For it to
match an OpenType feature contained in a font, it must follow the syntax
rules for tags. As specified in the OpenType specification, feature tags
contain four characters. Tag strings longer than four characters must be
ignored, user agents must not use a feature tag created by truncating the
string to four characters. Feature tags need only match a feature tag
defined in the font, they are not limited to explicitly registered
OpenType features. Fonts defining custom feature tags should follow the <a
href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
rules</a> defined in the OpenType specification <a
href="#OPENTYPE-FEATURES"
rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
Feature tags not present in the font are ignored; a user agent must not
attempt to synthesize fallback behavior based on these feature tags.
<p>If present, a value indicates an index used for glyph selection. An
<integer> value must be 0 or greater. A value of 0 indicates that
the feature is disabled. For boolean features, a value of 1 enables the
feature. For non-boolean features, a value of 1 or greater enables the
feature and indicates the feature selection index. A value of ‘<code
class=property>on</code>’ is synonymous with 1 and ‘<code
class=property>off</code>’ is synonymous with 0. If the value is
omitted, a value of 1 is assumed.
<pre>
font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
font-feature-settings: "liga" off; /* liga=0 no common ligatures */
font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
font-feature-settings: "palin" off; /* good idea but invalid tagname, ignored */
font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
</pre>
<p>Authors should generally use ‘<code class=property><a
href="#propdef-font-variant">font-variant</a></code>’ and its related
subproperties whenever possible and only use this property for special
cases where its use is the only way of accessing a particular infrequently
used font feature.
<p>Although specifically defined for OpenType feature tags, feature tags
for other modern font formats that support font features may be added in
the future.
<p class=issue>While the use of quotes distinguishes feature tags as
defined in an external resource, they still seem a bit clumsy.
<div class=example>
<p>The Japanese text below will be rendered with half-width kana
characters:</p>
<pre lang=ja>
body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
<p>毎日<a href="http://images.google.com/images?q=%E3%82%AB%E3%83%AC%E3%83%BC" style="text-decoration: none;">カレー</a>食べてるのに、飽きない</p>
</pre>
</div>
<h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
language override: the <a
href="#propdef-font-language-override">font-language-override</a> property</h3>
<table class=propdef id=namefont-language-override>
<tbody>
<tr>
<td>Name:
<td><dfn id=propdef-font-language-override>font-language-override</dfn>
<tr>
<td>Value:
<td>normal | inherit | <string>
<tr>
<td>Initial:
<td>normal
<tr>
<td>Applies to:
<td>all elements
<tr>
<td>Inherited:
<td>yes
<tr>
<td>Percentages:
<td>N/A
<tr>
<td>Media:
<td>visual
<tr>
<td>Computed value:
<td>as specified
</table>
<p>The value of ‘<code class=property>normal</code>’ implies that when
rendering with OpenType fonts the language of the document is used to
infer the OpenType language system, used to select language specific
features when rendering. The value of the <string> is a single
three-letter OpenType <a
href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
system tag</a>, defined in the layout tag registry of the OpenType
specification.
<div class=example>
<p>The <a
href="http://www.ohchr.org/EN/UDHR/Pages/Introduction.aspx">Universal
Declaration of Human Rights</a> has been translated into a wide variety
of languages. In Turkish, Article 9 of this document might be marked up
as below:</p>
<pre lang=tr><body lang="tr">
<h4>Madde 9</h4>
<p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
</pre>
<p>Here the user agent uses the value of the ‘<code
class=property>lang</code>’ attribute when rendering text and
appropriately renders this text without ‘<code
class=property>fi</code>’ ligatures. There is no need to use the
‘<code class=property><a
href="#propdef-font-language-override">font-language-override</a></code>’
property.</p>
<p>However, a given font may lack support for a specific language. In this
situation authors may need to use the typographic conventions of a
related language that are supported by that font:</p>
<pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
<h4>Члeн 9</h4>
<p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
</pre>
<p>The Macedonian text here will be rendered using Serbian typographic
conventions, with the assumption that the font specified supports
Serbian.</p>
</div>
<h2 id=rendering-considerations><span class=secno>7 </span>Resolving font
feature settings</h2>
<p>General and font-specific font feature property settings are resolved in
the order below, in low to high precedence. This ordering is used to
construct a combined list of font features that affect a given text run.
These features are applied on top of layout engine defaults.
<ol>
<li>If the font is defined via an @font-face rule, the font features
implied by the font-variant descriptor in the @font-face rule.
<li>If the font is defined via an @font-face rule, the font features
implied by the font-feature-settings descriptor in the @font-face rule.
<li>Font features implied by the value of the ‘<code class=property><a
href="#propdef-font-variant">font-variant</a></code>’ property, the
related font-variant subproperties and any other CSS property that may
use OpenType features (e.g. the ‘<code class=property><a
href="#propdef-font-kerning">font-kerning</a></code>’ property).
<li>Font features implied by the value of ‘<code class=property><a
href="#propdef-font-feature-settings">font-feature-settings</a></code>’
property.
</ol>
<p>This ordering allows authors to set up a general set of defaults for
fonts within their @font-face rules, then override them with property
settings for specific elements. General property settings override the
settings in @font-face rules and low-level font feature settings override
‘<code class=property><a
href="#propdef-font-variant">font-variant</a></code>’ property settings.
<p>For situations where the combined list of font feature settings contains
more than one value for the same feature, the last value is used. When a
font lacks support for a given underlying font feature, text is simply
rendered as if that font feature was not enabled; font fallback does not
occur and no attempt is made to synthesize the feature except where
explicitly noted for specific properties.
<div class=example>
<p>With the styles below, numbers are rendered proportionally when used
within a paragraph but are shown in tabular form within tables of prices:</p>
<pre>body {
font-variant-numeric: proportional-nums;
}
table.prices td {
font-variant-numeric: tabular-nums;
}
</pre>
</div>
<div class=example>
<p>When the font-variant descriptor is used within an @font-face rule, it
only applies to the font defined by that rule.</p>
<pre>@font-face {
font-family: MainText;
src: url(http://example.com/font.ttf);
font-variant: oldstyle-nums proportional-nums styleset(1,3);
}
body {
font-family: MainText, Helvetica;
}
table.prices td {
font-variant-numeric: tabular-nums;
}
</pre>
<p>In this case, old-style numerals will be used throughout but only where
the font "MainText" is used. Just as in the previous example, tabular
values will be used in price tables since ‘<code class=property><a
href="#tabular-nums">tabular-nums</a></code>’ appears in a general
style rule and its use is mutually exclusive with ‘<code
class=property><a
href="#proportional-nums">proportional-nums</a></code>’. Stylistic
alternate sets will only be used where MainText is used.</p>
</div>
<div class=example>
<p>The @font-face rule can also be used to access font features in locally
available fonts via the use of local() in the ‘<code class=property><a
href="#descdef-src">src</a></code>’ descriptor of the @font-face
definition:</p>
<pre>@font-face {
font-family: BodyText;
src: local("HiraMaruPro-W4");
font-variant: proportional-width;
font-feature-settings: "ital"; /* Latin italics within CJK text feature */
}
body { font-family: BodyText, serif; }
</pre>
<p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
text rendering occurs, Japanese kana will be proportionally spaced and
Latin text will be italicised. Text rendered with the fallback serif font
will use default rendering properties.</p>
</div>
<div class=example>
<p>In the example below, discretionary ligatures are enabled only for a
downloadable font but are disabled within spans of class "special":</p>
<pre>@font-face {
font-family: main;
src: url(fonts/ffmeta.woff) format("woff");
font-variant: discretionary-ligatures;
}
body { font-family: main, Helvetica; }
span.special { font-variant-ligatures: no-discretionary-ligatures; }
</pre>
<p>Adding an discretionary style rule with the @font-face above:</p>
<pre>body { font-family: main, Helvetica; }
span { font-feature-settings: "dlig"; }
span.special { font-variant-ligatures: no-discretionary-ligatures; }
</pre>
<p>Within spans of class "special", discretionary ligatures <em>will</em>
be rendered. This is because both the ‘<code class=property><a
href="#propdef-font-feature-settings">font-feature-settings</a></code>’
and ‘<code class=property><a
href="#propdef-font-variant-ligatures">font-variant-ligatures</a></code>’
properties apply to these spans. Although the ‘<code
class=css>no-discretionary ligatures</code>’ setting of ‘<code
class=property><a
href="#propdef-font-variant-ligatures">font-variant-ligatures</a></code>’
effectively disables the OpenType <code>dlig</code> feature, because the
‘<code class=property><a
href="#propdef-font-feature-settings">font-feature-settings</a></code>’
is resolved after that, the ‘<code class=property>dlig</code>’ value
reenables discretionary ligatures.</p>
</div>
<!-- simple example of using both font-variant subproperty and descriptor value -->
<!-- example showing conflicting values and how they are resolved -->
<h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
properties to CSS properties</h2>
<p><em>This appendix is included as background for some of the problems and
situations that are described in other sections. It should be viewed as
informative only.</em>
<p>Font properties in CSS are designed to be independent of the underlying
font formats used; they can be used to specify bitmap fonts, Type1 fonts,
SVG fonts in addition to the common TrueType and OpenType fonts. But there
are facets of the TrueType and OpenType formats that often cause confusion
for authors and present challenges to implementers on different platforms.
<p>Originally developed at Apple, TrueType was designed as an outline font
format for both screen and print. Microsoft joined Apple in developing the
TrueType format and both platforms have supported TrueType fonts since
then. Font data in the TrueType format consists of a set of tables
distinguished with common four-letter tag names, each containing a
specific type of data. For example, naming information, including
copyright and license information, is stored in the ‘<code
class=property>name</code>’ table. The character map (‘<code
class=property>cmap</code>’) table contains a mapping of character
encodings to glyphs. Apple later added additional tables for supporting
enhanced typographic functionality; these are now called Apple Advanced
Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
tables for advanced typography and called their format OpenType <a
href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
<p>In many cases the font data used under Microsoft Windows or Linux is
slightly different from the data used under Apple's Mac OS X because the
TrueType format allowed for variation across platforms. This includes font
metrics, names and character map data.
<p>Font family names for TrueType and OpenType fonts are contained in the
‘<code class=property>name</code>’ table, in name records with name ID
1. Mulitple names can be stored for different locales but Microsoft
recommends fonts always include at least a US English version of the name.
On Windows, the family name can only be used for a maximum of four faces;
for larger groupings the "preferred family" (name ID 16) or "WWS family"
(name ID 21) can be used. The full font name (name ID 4) and the
Postscript name (name ID 6) describe a single face uniquely. The bold face
of the Gill Sans family has a fullname of "Gill Sans Bold" and a
Postscript name of "GillSans-Bold". There can be multiple localized
versions of the fullname for a given face but the Postscript name is
always a unique name made from a limited set of ASCII characters.
<p>On various platforms, different names are used to search for a font. For
example, with the Windows GDI CreateIndirectFont API, either a family or
fullname can be used to lookup a face while on Mac OS X the
ATSFontFindFromName and ATSFontFindFromPostScriptName API calls are used
to lookup a given face using the fullname and Postscript name. Under
Linux, the fontconfig API allows fonts to be searched using any of these
names. In situations where platform API's automatically substitute other
font choices, it may be necessary to verify a returned font matches a
given name.
<p>The weight of a given face can be determined via the usWeightClass field
of the OS/2 table or inferred from the style name (name ID 2). Likewise,
the width can be determined via the usWidthClass of the OS/2 table or
inferred from the style name. For historical reasons, font designers have
sometimes skewed values in the OS/2 table to work around problems in the
Windows GDI API.
<p>Rendering complex scripts that use contextual shaping such as Thai,
Arabic and Devanagari requires features present only in OpenType or AAT
fonts. Currently, complex script rendering is supported on Windows and
Linux using OpenType font features while AAT font features are used under
Mac OS X. Apple has indicated it intends to support complex script
rendering using OpenType font features in the future.
<p class=issue>Need to define normatively how WWS names are handled across
platforms.
<h2 class=no-num id=font-licensing>Appendix B: Font licensing issues</h2>
<p><em>This appendix is informative only.</em>
<p>The use of fonts on the web is often surrounded in controversy. Font
designers expend huge amounts of effort to create their designs,
painstakingly refining letterforms and tuning font data to assure that the
letterforms appear as desired both in print and on the screen. As a result
they often license their fonts very carefully, often with somewhat complex
terms. Authors who want to use specific fonts via a downloadable font
mechanism must always carefully verify that their intended use is within
the scope of the font license. Many commercial fonts presently do not
allow web downloading of their fonts in any form. Font formats often store
references to the font license within the font data itself. When in doubt,
it is best to verify with the font designer directly. Vendors that bundle
fonts with their products are also strongly encouraged to carefully
explain the license details that covers the fonts they bundle.
<div class=example>
<p>An author would like to use <a
href="http://www.typography.com/fonts/font_overview.php?productLineID=
100008">Gotham</a>, a font designed by Hoefler & Frere-Jones, as a
downloadable font for their webpages. But the <a
href="http://www.typography.com/home/eula.php">end-user license
agreement</a> that covers Gotham specifically notes that usage via
@font-face rules in CSS style sheets is not allowed. The author cannot
link to this font in their web pages.</p>
</div>
<div class=example>
<p>An author wants to use <a
href="http://scripts.sil.org/gentium">Gentium</a>, a font developed by
SIL International. This font is licensed under the terms of the <a
href="http://scripts.sil.org/ofl">Open Font License</a>, so as long as
the author follows the relatively liberal terms of this license, they can
use Gentium as a downloadable font for their web pages.</p>
</div>
<h2 class=no-num id=font-feature-values-DOM>Appendix C: DOM Interfaces</h2>
<p><em>This appendix is normative.</em>
<p>Font feature values defined within <code>@font-feature-values</code>
rules are accessible via the following modifications to the CSS Object
Model.
<dl>
<dt><b>Interface <i><a id=DOM-CSSRule name=DOM-CSSRule>CSSRule</a></i></b>
<dd>
<p>The following additional rule type is added to the
<code>CSSRule</code> interface.</p>
<dl>
<dt><b>IDL Definition</b>
<dd>
<div class=idl-code>
<pre>
interface CSSRule {
...
const unsigned short FONT_FEATURE_VALUES_RULE = 11;
...
};</pre>
</div>
</dd>
<!-- IDL -->
</dl>
<dt><b>Interface <i><a id=DOM-CSSFontFeatureValuesRule
name=DOM-CSSFontFeatureValuesRule>CSSFontFeatureValuesRule</a></i></b>
<dd>
<p> The <code>CSSFontFeatureValuesRule</code> interface represents font
feature selector values for a given set of font families.</p>
<dl>
<dt> <br>
<b>IDL Definition</b>
<dd>
<div class=idl-code>
<pre>
interface CSSFontFeatureValuesRule : CSSRule {
attribute DOMString fontFamily;
// raises(DOMException) on setting
attribute DOMString valueText;
// raises(DOMException) on setting
};
</pre>
</div>
<br>
<dt><b>Attributes</b>
<dd>
<dl>
<dt><code class=attribute-name><a
id=DOM-CSSFontFeatureValuesRule-fontFamily
name=DOM-CSSFontFeatureValuesRule-fontFamily>fontFamily</a></code> of
type <code>DOMString</code>
<dd>This attribute represents the list of font families for which a
particular set of values are defined. The syntax is the same as that
of the font-family property.
</dl>
<dd>
<dl>
<dt><code class=attribute-name><a
id=DOM-CSSFontFeatureValuesRule-valueText
name=DOM-CSSFontFeatureValuesRule-valueText>valueText</a></code> of
type <code>DOMString</code>
<dd>Parsable text representing the set of feature values defined for a
given set of font families.
</dl>
<dt><b>Exceptions on setting</b>
</dl>
<dl>
<dt><code>DOMException SYNTAX_ERR</code>
<dd>Thrown when the specified string value has a syntax error or is
unparsable.
</dl>
<dt><b>No Methods</b>
</dl>
<h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
<h3 class=no-num id=recent-changes> Changes from the <a
href="http://www.w3.org/TR/2011/WD-css3-fonts-20110324/">March 2011 CSS3
Fonts Working Draft</a></h3>
<p>Major changes include:
<ul>
<li>Made same-origin wording normative and marked it at-risk
<li>Simplified definition of subscript/superscript variant property
<li>Trimmed some font-variant property values and renamed others
<li>Added more examples for various font variant value types
<li>Added DOM interface definitions for @font-feature-values rules
</ul>
<h2 class=no-num id=acknowledgments>Acknowledgments</h2>
<p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
their help and feedback. John Hudson was kind enough to take the time to
explain the subtleties of OpenType language tags and provided the example
of character variant usage for displaying text on Byzantine seals. Ken
Lunde and Eric Muller provided valuable feedback on CJK OpenType features
and Unicode variation selectors. The idea for supporting font features by
using font-variant subproperties originated with Håkon Wium Lie, Adam
Twardoch and Tal Leming. Thanks also to House Industries for allowing the
use of Ed Interlock in the discretionary ligatures example.
<p>A special thanks to Robert Bringhurst for the sublime mind expansion
that is <em>The Elements of Typographic Style</em>.
<h2 class=no-num id=references>References</h2>
<h3 class=no-num id=normative-references>Normative References</h3>
<!--begin-normative-->
<!-- Sorted by label -->
<dl class=bibliography>
<dt style="display: none"><!-- keeps the doc valid if the DL is empty -->
<!---->
<dt id=CHARMOD>[CHARMOD]
<dd>Martin J. Dürst; et al. <a
href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
2005. W3C Recommendation. URL: <a
href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
</dd>
<!---->
<dt id=CORS>[CORS]
<dd>Anne van Kesteren. <a
href="http://www.w3.org/TR/2010/WD-cors-20100727/"><cite>Cross-Origin
Resource Sharing.</cite></a> 27 July 2010. W3C Working Draft. (Work in
progress.) URL: <a
href="http://www.w3.org/TR/2010/WD-cors-20100727/">http://www.w3.org/TR/2010/WD-cors-20100727/</a>
</dd>
<!---->
<dt id=CSS21>[CSS21]
<dd>Bert Bos; et al. <a
href="http://www.w3.org/TR/2011/REC-CSS2-20110607/"><cite>Cascading Style
Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
2011. W3C Recommendation. URL: <a
href="http://www.w3.org/TR/2011/REC-CSS2-20110607/">http://www.w3.org/TR/2011/REC-CSS2-20110607/</a>
</dd>
<!---->
<dt id=HTML5>[HTML5]
<dd>Ian Hickson. <a
href="http://www.w3.org/TR/2011/WD-html5-20110525/"><cite>HTML5.</cite></a>
25 May 2011. W3C Working Draft. (Work in progress.) URL: <a
href="http://www.w3.org/TR/2011/WD-html5-20110525/">http://www.w3.org/TR/2011/WD-html5-20110525/</a>
</dd>
<!---->
<dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
<dd><a
href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
technology — Coding of audio-visual objects — Part 22: Open Font
Format.</cite></a> International Organization for Standardization.
ISO/IEC 14496-22:2009. URL: <a
href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip">http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip</a>
</dd>
<!---->
<dt id=OPENTYPE>[OPENTYPE]
<dd><a
href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
specification.</cite></a> Microsoft. URL: <a
href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
</dd>
<!---->
<dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
<dd><a
href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
feature registry.</cite></a> Microsoft. URL: <a
href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
</dd>
<!---->
<dt id=UAX15>[UAX15]
<dd>Mark Davis. <a
href="http://www.unicode.org/reports/tr15/tr15-33.html"><cite>Unicode
Normalization Forms.</cite></a> 17 September 2010. Unicode Standard Annex
#15. URL: <a
href="http://www.unicode.org/reports/tr15/tr15-33.html">http://www.unicode.org/reports/tr15/tr15-33.html</a>
</dd>
<!---->
<dt id=UAX29>[UAX29]
<dd>Mark Davis. <a
href="http://www.unicode.org/reports/tr29/tr29-17.html"><cite>Unicode
Text Segmentation.</cite></a> 8 October 2010. Unicode Standard Annex #29.
URL: <a
href="http://www.unicode.org/reports/tr29/tr29-17.html">http://www.unicode.org/reports/tr29/tr29-17.html</a>
</dd>
<!---->
<dt id=UNICODE6>[UNICODE6]
<dd>The Unicode Consortium. <a
href="http://www.unicode.org/versions/Unicode6.0.0/"><cite>The Unicode
Standard, Version 6.0.0.</cite></a> Defined by: The Unicode Standard,
Version 6.0.0 (Mountain View, CA: The Unicode Consortium, 2011. ISBN
978-1-936213-01-6) URL: <a
href="http://www.unicode.org/versions/Unicode6.0.0/">http://www.unicode.org/versions/Unicode6.0.0/</a>
</dd>
<!---->
</dl>
<!--end-normative-->
<!--{{!CSS21}}-->
<!--{{!OPENTYPE}}-->
<!--{{!OPENTYPE-FEATURES}}-->
<!--{{!OPEN-FONT-FORMAT}}-->
<!--{{!UNICODE6}}-->
<!--{{!UAX15}}-->
<!--{{!UAX29}}-->
<!--{{!CORS}}-->
<!--{{!HTML5}}-->
<!--{{!CHARMOD}}-->
<h3 class=no-num id=other-references>Other References</h3>
<!--begin-informative-->
<!-- Sorted by label -->
<dl class=bibliography>
<dt style="display: none"><!-- keeps the doc valid if the DL is empty -->
<!---->
<dt id=AAT-FEATURES>[AAT-FEATURES]
<dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
Advanced Typography font feature registry.</cite></a> Apple. URL: <a
href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
</dd>
<!---->
<dt id=ARABIC-TYPO>[ARABIC-TYPO]
<dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
<!---->
<dt id=CHARMOD-NORM>[CHARMOD-NORM]
<dd>François Yergeau; et al. <a
href="http://www.w3.org/TR/2005/WD-charmod-norm-20051027/"><cite>Character
Model for the World Wide Web 1.0: Normalization.</cite></a> 27 October
2005. W3C Working Draft. (Work in progress.) URL: <a
href="http://www.w3.org/TR/2005/WD-charmod-norm-20051027/">http://www.w3.org/TR/2005/WD-charmod-norm-20051027/</a>
</dd>
<!---->
<dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
<dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
<!---->
<dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
<dd>L. David Baron. <a
href="http://www.w3.org/TR/2011/WD-css3-conditional-20110901/"><cite>CSS
Conditional Rules Module Level 3.</cite></a> 1 September 2011. W3C
Working Draft. (Work in progress.) URL: <a
href="http://www.w3.org/TR/2011/WD-css3-conditional-20110901/">http://www.w3.org/TR/2011/WD-css3-conditional-20110901/</a>
</dd>
<!---->
<dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
<dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
ISBN 0-201-17633-5.</dd>
<!---->
<dt id=ELEMTYPO>[ELEMTYPO]
<dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
3.1.</cite> Hartley & Marks. 2005. ISBN 0-88179-206-3.</dd>
<!---->
<dt id=LANGCULTTYPE>[LANGCULTTYPE]
<dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
ISBN 1-932026-01-0.</dd>
<!---->
<dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
<dd><a
href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
User Guide.</cite></a> FontShop International. URL: <a
href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
</dd>
<!---->
<dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
<dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
Tragedy at Low-Resolution Revisited.</cite></a> 14 March 2011. URL: <a
href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
<!---->
<dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
<dd>John Hudson. <a
href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
</dd>
<!---->
</dl>
<!--end-informative-->
<!--{{ARABIC-TYPO}}-->
<!--{{CJKV-INFO-PROCESSING}}-->
<!--{{DIGITAL-TYPOGRAPHY}}-->
<!--{{ELEMTYPO}}-->
<!--{{LANGCULTTYPE}}-->
<!--{{OPENTYPE-FONT-GUIDE}}-->
<!--{{RASTER-TRAGEDY}}-->
<!--{{WINDOWS-GLYPH-PROC}}-->
<!--{{CHARMOD-NORM}}-->
<!--{{AAT-FEATURES}}-->
<!--{{CSS3-CONDITIONAL}}-->
<h2 class=no-num id=index>Index</h2>
<!--begin-index-->
<ul class=indexlist>
<li><absolute-size>
<ul>
<li>definition of, <a href="#ltabsolute-sizegt"
title="<absolute-size> definition of"><strong>3.5</strong></a>
</ul>
<li>all-petite-caps, <a href="#all-petite-caps"
title=all-petite-caps><strong>6.6</strong></a>
<li>all-small-caps, <a href="#all-small-caps"
title=all-small-caps><strong>6.6</strong></a>
<li>annotation(<feature-value-name>), <a
href="#annotationltfeature-value-namegt"
title="annotation(<feature-value-name>)"><strong>6.8</strong></a>
<li>aspect value, <a href="#aspect0" title="aspect
value"><strong>3.6</strong></a>
<li>at-rules, <a href="#at-rule" title=at-rules>4.1</a>
<li><var><caps-value></var>, <a href="#ltcaps-valuegt"
title="<caps-value>"><strong>6.6</strong></a>
<li>character-variant(<feature-value-name>
[,<feature-value-name>]*), <a
href="#character-variantltfeature-value-namegt"
title="character-variant(<feature-value-name>
[,<feature-value-name>]*)"><strong>6.8</strong></a>
<li>common-ligatures, <a href="#common-ligatures"
title=common-ligatures><strong>6.5</strong></a>
<li><var><common-lig-values></var>, <a href="#ltcommon-lig-values"
title="<common-lig-values>"><strong>6.5</strong></a>
<li>contextual, <a href="#contextual"
title=contextual><strong>6.8</strong></a>
<li><var><contextual-alt-values></var>, <a
href="#ltcontextual-alt-valuesgt"
title="<contextual-alt-values>"><strong>6.8</strong></a>
<li>cursive, definition of, <a href="#cursive0" title="cursive, definition
of"><strong>#</strong></a>
<li>diagonal-fractions, <a href="#diagonal-fractions"
title=diagonal-fractions><strong>6.7</strong></a>
<li>discretionary-ligatures, <a href="#discretionary-ligatures"
title=discretionary-ligatures><strong>6.5</strong></a>
<li><var><discretionary-lig-values></var>, <a
href="#ltdiscretionary-lig-values"
title="<discretionary-lig-values>"><strong>6.5</strong></a>
<li><var><east-asian-variant-values></var>, <a
href="#lteast-asian-variant-valuesgt"
title="<east-asian-variant-values>"><strong>6.10</strong></a>
<li><var><east-asian-width-values></var>, <a
href="#lteast-asian-width-valuesgt"
title="<east-asian-width-values>"><strong>6.10</strong></a>
<li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
of"><strong>#</strong></a>
<li><var><feature-index></var>, <a href="#ltfeature-indexgt"
title="<feature-index>"><strong>6.9</strong></a>
<li><var><feature-tag-value></var>, <a href="#ltfeature-tag-valuegt"
title="<feature-tag-value>"><strong>6.12</strong></a>
<li><var><feature-value-list></var>, <a
href="#ltfeature-value-listgt"
title="<feature-value-list>"><strong>6.9</strong></a>
<li><var><feature-value-name></var>, <a
href="#ltfeature-value-namegt"
title="<feature-value-name>"><strong>6.9</strong></a>
<li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
<li><font-description>
<ul>
<li>definition of, <a href="#ltfont-descriptiongt"
title="<font-description> definition of"><strong>4.1</strong></a>
</ul>
<li>@font-face, <a href="#font-face"
title="@font-face"><strong>4.1</strong></a>, <a href="#font-face0"
title="@font-face">4.1</a>, <a href="#font-face1"
title="@font-face">4.3</a>
<li><font-face-name>
<ul>
<li>definition of, <a href="#ltfont-face-namegt"
title="<font-face-name> definition of"><strong>4.3</strong></a>
</ul>
<li>font-family, <a href="#descdef-font-family"
title=font-family><strong>4.2</strong></a>, <a href="#ltfont-familygt"
title="<font-family>"><strong>6.9</strong></a>, <a
href="#propdef-font-family" title=font-family><strong>3.1</strong></a>
<li>font-feature-settings, <a href="#descdef-font-feature-settings"
title=font-feature-settings><strong>4.6</strong></a>, <a
href="#propdef-font-feature-settings"
title=font-feature-settings><strong>6.12</strong></a>
<li>font-kerning, <a href="#propdef-font-kerning"
title=font-kerning><strong>6.3</strong></a>
<li>font-language-override, <a href="#propdef-font-language-override"
title=font-language-override><strong>6.13</strong></a>
<li>font-size, <a href="#propdef-font-size"
title=font-size><strong>3.5</strong></a>
<li>font-size-adjust, <a href="#propdef-font-size-adjust"
title=font-size-adjust><strong>3.6</strong></a>
<li>font-stretch, <a href="#descdef-font-stretch"
title=font-stretch><strong>4.4</strong></a>, <a
href="#propdef-font-stretch" title=font-stretch><strong>3.3</strong></a>
<li>font-style, <a href="#descdef-font-style"
title=font-style><strong>4.4</strong></a>, <a href="#propdef-font-style"
title=font-style><strong>3.4</strong></a>
<li>font-synthesis, <a href="#propdef-font-synthesis"
title=font-synthesis><strong>3.8</strong></a>
<li>font-variant, <a href="#descdef-font-variant"
title=font-variant><strong>4.6</strong></a>, <a
href="#propdef-font-variant" title=font-variant><strong>6.11</strong></a>
<li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
title=font-variant-alternates><strong>6.8</strong></a>
<li>font-variant-caps, <a href="#propdef-font-variant-caps"
title=font-variant-caps><strong>6.6</strong></a>
<li><var><font-variant-css21></var>, <a
href="#ltfont-variant-css21gt"
title="<font-variant-css21>"><strong>3.7</strong></a>
<li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
title=font-variant-east-asian><strong>6.10</strong></a>
<li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
title=font-variant-ligatures><strong>6.5</strong></a>
<li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
title=font-variant-numeric><strong>6.7</strong></a>
<li>font-variant-position, <a href="#propdef-font-variant-position"
title=font-variant-position><strong>6.4</strong></a>
<li><var><font-variant-value></var>, <a
href="#ltfont-variant-valuegt"
title="<font-variant-value>"><strong>6.9</strong></a>
<li><var><font-variant-value-definition></var>, <a
href="#ltfont-variant-value-definitiongt"
title="<font-variant-value-definition>"><strong>6.9</strong></a>
<li>font-weight, <a href="#descdef-font-weight"
title=font-weight><strong>4.4</strong></a>, <a
href="#propdef-font-weight" title=font-weight><strong>3.2</strong></a>
<li>full-width, <a href="#full-width"
title=full-width><strong>6.10</strong></a>
<li>historical-forms, <a href="#historical-forms"
title=historical-forms><strong>6.8</strong></a>
<li>historical-ligatures, <a href="#historical-ligatures"
title=historical-ligatures><strong>6.5</strong></a>
<li><var><historical-lig-values></var>, <a
href="#lthistorical-lig-values"
title="<historical-lig-values>"><strong>6.5</strong></a>
<li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
<li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
<li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
<li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
<li><length>, <a href="#ltlengthgt" title="<length>">3.5</a>
<li>lining-nums, <a href="#lining-nums"
title=lining-nums><strong>6.7</strong></a>
<li>monospace, definition of, <a href="#monospace0" title="monospace,
definition of"><strong>#</strong></a>
<li>no-common-ligatures, <a href="#no-common-ligatures"
title=no-common-ligatures><strong>6.5</strong></a>
<li>no-contextual, <a href="#no-contextual"
title=no-contextual><strong>6.8</strong></a>
<li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
title=no-discretionary-ligatures><strong>6.5</strong></a>
<li>no-historical-ligatures, <a href="#no-historical-ligatures"
title=no-historical-ligatures><strong>6.5</strong></a>
<li><number>, <a href="#ltnumbergt" title="<number>">3.6</a>
<li><var><numeric-figure-values></var>, <a
href="#ltnumeric-figure-valuesgt"
title="<numeric-figure-values>"><strong>6.7</strong></a>
<li><var><numeric-fraction-values></var>, <a
href="#ltnumeric-fraction-valuesgt"
title="<numeric-fraction-values>"><strong>6.7</strong></a>
<li><var><numeric-spacing-values></var>, <a
href="#ltnumeric-spacing-valuesgt"
title="<numeric-spacing-values>"><strong>6.7</strong></a>
<li>oldstyle-nums, <a href="#oldstyle-nums"
title=oldstyle-nums><strong>6.7</strong></a>
<li>ornaments(<feature-value-name>), <a
href="#ornamentsltfeature-value-namegt"
title="ornaments(<feature-value-name>)"><strong>6.8</strong></a>
<li><percentage>, <a href="#ltpercentagegt"
title="<percentage>">3.5</a>
<li>petite-caps, <a href="#petite-caps"
title=petite-caps><strong>6.6</strong></a>
<li>proportional-nums, <a href="#proportional-nums"
title=proportional-nums><strong>6.7</strong></a>
<li>proportional-width, <a href="#proportional-width"
title=proportional-width><strong>6.10</strong></a>
<li><relative-size>
<ul>
<li>definition of, <a href="#ltrelative-sizegt"
title="<relative-size> definition of"><strong>3.5</strong></a>
</ul>
<li>ruby, <a href="#ruby" title=ruby><strong>6.8</strong></a>
<li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
definition of"><strong>#</strong></a>
<li>serif, definition of, <a href="#serif0" title="serif, definition
of"><strong>#</strong></a>
<li>simplified, <a href="#simplified"
title=simplified><strong>6.10</strong></a>
<li>slashed-zero, <a href="#slashed-zero"
title=slashed-zero><strong>6.7</strong></a>
<li>small-caps, <a href="#small-caps"
title=small-caps><strong>6.6</strong></a>
<li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
<li>stacked-fractions, <a href="#stacked-fractions"
title=stacked-fractions><strong>6.7</strong></a>
<li>styleset(<feature-value-name> [,<feature-value-name>]*),
<a href="#stylesetltfeature-value-namegt"
title="styleset(<feature-value-name>
[,<feature-value-name>]*)"><strong>6.8</strong></a>
<li>stylistic(<feature-value-name>), <a
href="#stylisticltfeature-value-namegt"
title="stylistic(<feature-value-name>)"><strong>6.8</strong></a>
<li>swash(<feature-value-name>), <a
href="#swashltfeature-value-namegt"
title="swash(<feature-value-name>)"><strong>6.8</strong></a>
<li>tabular-nums, <a href="#tabular-nums"
title=tabular-nums><strong>6.7</strong></a>
<li>titling-caps, <a href="#titling-caps"
title=titling-caps><strong>6.6</strong></a>
<li>traditional, <a href="#traditional"
title=traditional><strong>6.10</strong></a>
<li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
<li>unicode-range, <a href="#descdef-unicode-range"
title=unicode-range><strong>4.5</strong></a>
<li><urange>
<ul>
<li>definition of, <a href="#lturangegt" title="<urange>
definition of"><strong>4.5</strong></a>
</ul>
</ul>
<!--end-index-->
<h2 class=no-num id=property-index>Property index</h2>
<!--begin-properties-->
<table class=proptable>
<thead>
<tr>
<th>Property
<th>Values
<th>Initial
<th>Applies to
<th>Inh.
<th>Percentages
<th>Media
<tbody>
<tr>
<th><a class=property href="#propdef-font">font</a>
<td>[ [ <‘font-style’> || <font-variant-css21> ||
<‘font-weight’> ]? <‘font-size’> [ /
<‘line-height’> ]? <‘font-family’> ] | caption | icon |
menu | message-box | small-caption | status-bar | inherit
<td>see individual properties
<td>all elements
<td>yes
<td>see individual properties
<td>visual
<tr>
<th><a class=property href="#descdef-font-family">font-family</a>
<td>[[ <family-name> | <generic-family> ] [, <family-name> |
<generic-family>]* ] | inherit
<td>depends on user agent
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property
href="#propdef-font-feature-settings">font-feature-settings</a>
<td>normal | <feature-tag-value> [, <feature-tag-value>]*
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property href="#propdef-font-kerning">font-kerning</a>
<td>auto | normal | none
<td>auto
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property
href="#propdef-font-language-override">font-language-override</a>
<td>normal | inherit | <string>
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property href="#propdef-font-size">font-size</a>
<td><absolute-size> | <relative-size> | <length> |
<percentage> | inherit
<td>medium
<td>all elements
<td>yes
<td>refer to parent element's font size
<td>visual
<tr>
<th><a class=property
href="#propdef-font-size-adjust">font-size-adjust</a>
<td><number> | none | inherit
<td>none
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property href="#descdef-font-stretch">font-stretch</a>
<td>normal | ultra-condensed | extra-condensed | condensed |
semi-condensed | semi-expanded | expanded | extra-expanded |
ultra-expanded | inherit
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property href="#descdef-font-style">font-style</a>
<td>normal | italic | oblique | inherit
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
<td>none | [ weight || style ]
<td>weight style
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property href="#propdef-font-variant">font-variant</a>
<td>normal | inherit | [ <common-lig-values> ||
<discretionary-lig-values> || <historical-lig-values> ||
<contextual-alt-values> || stylistic(<feature-value-name>)
|| historical-forms || styleset(<feature-value-name> [,
<feature-value-name>]*) ||
character-variant(<feature-value-name>
[,<feature-value-name>]*) || swash(<feature-value-name>) ||
ornaments(<feature-value-name>) ||
annotation(<feature-value-name>) || ruby || <caps-value> ||
<numeric-figure-values> || <numeric-spacing-values> ||
<numeric-fraction-values> || slashed-zero ||
<east-asian-variant-values> || <east-asian-width-values> ]
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property
href="#propdef-font-variant-alternates">font-variant-alternates</a>
<td>normal | inherit | [ <contextual-alt-values> ||
stylistic(<feature-value-name>) || historical-forms ||
styleset(<feature-value-name> [, <feature-value-name>]*) ||
character-variant(<feature-value-name>
[,<feature-value-name>;]*) || swash(<feature-value-name>)
|| ornaments(<feature-value-name>) ||
annotation(<feature-value-name>) || ruby ]
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property
href="#propdef-font-variant-caps">font-variant-caps</a>
<td>normal | inherit | <caps-value>
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property
href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
<td>normal | inherit | [ <east-asian-variant-values> ||
<east-asian-width-values> ]
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property
href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
<td>normal | inherit | [ <common-lig-values> ||
<discretionary-lig-values> || <historical-lig-values> ]
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property
href="#propdef-font-variant-numeric">font-variant-numeric</a>
<td>normal | inherit | [ <numeric-figure-values> ||
<numeric-spacing-values> || <numeric-fraction-values> ||
slashed-zero ]
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property
href="#propdef-font-variant-position">font-variant-position</a>
<td>normal | sub | super | ordinal
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
<tr>
<th><a class=property href="#descdef-font-weight">font-weight</a>
<td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
| 700 | 800 | 900 | inherit
<td>normal
<td>all elements
<td>yes
<td>N/A
<td>visual
</table>
<!--end-properties-->
<!-- descriptors -->
</html>
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Local variables:
mode: sgml
sgml-declaration:"~/SGML/HTML4.decl"
sgml-default-doctype-name:"html"
sgml-minimize-attributes:t
sgml-nofill-elements:("pre" "style" "br")
sgml-live-element-indicator:t
sgml-omittag:nil
sgml-shorttag:nil
sgml-namecase-general:t
sgml-general-insert-case:lower
sgml-always-quote-attributes:t
sgml-indent-step:nil
sgml-indent-data:t
sgml-parent-document:nil
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
-->
<!--
to do:
- wording of OpenType family name handling
- handling combining sequences in the font matching algorithm
- fix-up fi ligature example
-->