discontinued / server · Files

index.html 81.5 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 
<!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 Device Adaptation</title>
  <link href=default.css rel=stylesheet type="text/css">
  <link href="http://www.w3.org/StyleSheets/TR/W3C-WD" rel=stylesheet
  type="text/css">

 <body class=draft>
  <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 Device Adaptation</h1>

   <h2 class="no-num no-toc" id=longstatus-date>W3C Working Draft 15
    September 2011</h2>

   <dl>
    <dt>This version:

    <dd><a
     href="http://www.w3.org/TR/2011/WD-css-device-adapt-20110915/">http://www.w3.org/TR/2011/WD-css-device-adapt-20110915/</a>

    <dt>Latest version:

    <dd><a
     href="http://www.w3.org/TR/css-device-adapt/">http://www.w3.org/TR/css-device-adapt/</a>

    <dt>Previous version:

    <dd>None

    <dt>Editor:

    <dd><a href="mailto:rune@opera.com">Rune Lillesveen</a> (<a
     href="http://www.opera.com/">Opera Software</a>)
   </dl>
   <!--begin-copyright-->
   <p class=copyright><a
    href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
    rel=license>Copyright</a> &copy; 2011 <a
    href="http://www.w3.org/"><acronym title="World Wide Web
    Consortium">W3C</acronym></a><sup>&reg;</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 specification provides a way for an author to specify, in CSS, the
   size, zoom factor, and orientation of the viewport that is used as the
   base for the initial containing block.

  <h2 class="no-num no-toc" id=status-of-this-document>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 &#8220;css-device-adapt&#8221; in the subject, preferably like this:
   &#8220;[<!---->css-device-adapt<!---->] <em>&hellip;summary of
   comment&hellip;</em>&#8221;

  <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-->

  <p>This is the first public Working Draft of the CSS Device Adaptation
   Module.

  <h2 class="no-num no-toc" id=table-of-contents>Table of Contents</h2>
  <!--begin-toc-->

  <ul class=toc>
   <li><a href="#introduction"><span class=secno>1. </span>Introduction</a>

   <li><a href="#values"><span class=secno>2. </span>Values</a>

   <li><a href="#the-viewport"><span class=secno>3. </span>The viewport</a>

   <li><a href="#the-viewport-rule"><span class=secno>4. </span>The <code
    class=css>@viewport</code> rule</a>
    <ul class=toc>
     <li><a href="#syntax"><span class=secno>4.1. </span>Syntax</a>
    </ul>

   <li><a href="#viewport-properties"><span class=secno>5. </span>Viewport
    properties</a>
    <ul class=toc>
     <li><a href="#the-lsquomin-widthrsquo-and-lsquomax-wid"><span
      class=secno>5.1. </span>The &lsquo;<code
      class=property>min-width</code>&rsquo; and &lsquo;<code
      class=property>max-width</code>&rsquo; properties</a>

     <li><a href="#the-lsquowidthrsquo-shorthand-property"><span
      class=secno>5.2. </span>The &lsquo;<code
      class=property>width</code>&rsquo; shorthand property</a>

     <li><a href="#the-lsquomin-heightrsquo-and-lsquomax-he"><span
      class=secno>5.3. </span>The &lsquo;<code
      class=property>min-height</code>&rsquo; and &lsquo;<code
      class=property>max-height</code>&rsquo; properties</a>

     <li><a href="#the-lsquoheightrsquo-shorthand-property"><span
      class=secno>5.4. </span>The &lsquo;<code
      class=property>height</code>&rsquo; shorthand property</a>

     <li><a href="#the-lsquozoomrsquo-property"><span class=secno>5.5.
      </span>The &lsquo;<code class=property
      title="zoom!!property">zoom</code>&rsquo; property</a>

     <li><a href="#the-lsquomin-zoomrsquo-property"><span class=secno>5.6.
      </span>The &lsquo;<code class=property>min-zoom</code>&rsquo;
      property</a>

     <li><a href="#the-lsquomax-zoomrsquo-property"><span class=secno>5.7.
      </span>The &lsquo;<code class=property>max-zoom</code>&rsquo;
      property</a>

     <li><a href="#the-lsquouser-zoomrsquo-property"><span class=secno>5.8.
      </span>The &lsquo;<code class=property>user-zoom</code>&rsquo;
      property</a>

     <li><a href="#the-lsquoorientationrsquo-property"><span class=secno>5.9.
      </span>The &lsquo;<code class=property>orientation</code>&rsquo;
      property</a>

     <li><a href="#the-lsquoresolutionrsquo-property"><span class=secno>5.10.
      </span>The &lsquo;<code class=property>resolution</code>&rsquo;
      property</a>
    </ul>

   <li><a href="#constraining-viewport-property-values"><span class=secno>6.
    </span>Constraining viewport property values</a>
    <ul class=toc>
     <li><a href="#definitions"><span class=secno>6.1. </span>Definitions</a>
      

     <li><a href="#constraining-procedure"><span class=secno>6.2. </span>The
      procedure</a>
    </ul>

   <li><a href="#media-queries"><span class=secno>7. </span>Media Queries</a>
    

   <li><a href="#cssom"><span class=secno>8. </span>CSSOM</a>

   <li><a href="#conformance"><span class=secno>9. </span>Conformance</a>

   <li><a href="#viewport-meta-element"><span class=secno>10. </span>Viewport
    <code class=html>META</code> element</a>
    <ul class=toc>
     <li><a href="#ua-stylesheet"><span class=secno>10.1. </span>UA
      stylesheet</a>

     <li><a href="#meta-properties"><span class=secno>10.2.
      </span>Properties</a>

     <li><a href="#parsing-algorithm"><span class=secno>10.3. </span>Parsing
      algorithm</a>

     <li><a href="#translation-into-viewport-properties"><span
      class=secno>10.4. </span>Translation into <code
      class=css>@viewport</code> properties</a>
    </ul>

   <li><a href="#handling-auto-zoom"><span class=secno>11. </span>Handling
    &lsquo;<code class=css title="auto!!zoom">auto</code>&rsquo; for
    &lsquo;<code class=property title="zoom!!property">zoom</code>&rsquo;</a>
    

   <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="#property-index">Property index</a>

   <li class=no-num><a href="#index">Index</a>
  </ul>
  <!--end-toc-->

  <h2 id=introduction><span class=secno>1. </span>Introduction</h2>

  <p><em>This section is not normative.</em>

  <p>CSS 2.1 <a href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
   specifies an <a
   href="http://www.w3.org/TR/CSS21/visudet.html#containing-block-details">
   initial containing block</a> for continuous media that has the dimensions
   of the <a href="http://www.w3.org/TR/CSS21/visuren.html#viewport">
   viewport</a>. Mobile/handheld device browsers have a viewport that is
   generally a lot narrower than a desktop browser window at a zoom level
   that gives a CSS pixel size <a
   href="http://www.w3.org/TR/CSS21/syndata.html#length-units">recommended
   </a> by CSS 2.1.

  <p>The narrow viewport is a problem for documents designed to look good in
   desktop browsers. The result is that mobile browser vendors use a fixed
   initial containing block size that is different from the viewport size,
   and close to that of a typical desktop browser window. In addition to
   scrolling or panning, zooming is often used to change between an overview
   of the document and zoom in on particular areas of the document to read
   and interact with.

  <p>Certain DOCTYPEs (for instance XHTML Mobile Profile) are used to
   recognize mobile documents which are assumed to be designed for handheld
   devices, hence using the viewport size as the initial containing block
   size.

  <p>Additionally, an HTML <code class=html>META</code> tag has been
   introduced for allowing an author to specify the size of the initial
   containing block, and the initial zoom factor directly. It was first
   implemented by Apple for the Safari/iPhone browser, but has since been
   implemented for the Opera, Android, and Fennec browsers. These
   implementations are not fully interoperable and this specification is an
   attempt at standardizing the functionality provided by the viewport <code
   class=html>META</code> tag in CSS.

  <h2 id=values><span class=secno>2. </span>Values</h2>

  <p>This specification follows the <a
   href="http://www.w3.org/TR/css3-syntax/#property-defs">CSS property
   definition conventions</a> from <a href="#CSS3SYN"
   rel=biblioentry>[CSS3SYN]<!--{{!CSS3SYN}}--></a>.

  <p>Value types are defined in <a href="#CSS3VAL"
   rel=biblioentry>[CSS3VAL]<!--{{!CSS3VAL}}--></a>.

  <h2 id=the-viewport><span class=secno>3. </span>The viewport</h2>

  <p>This specification introduces a way of overriding the size of the
   viewport provided by the user agent (UA). Because of this, we need to
   introduce the difference between the <a href="#initial-viewport">initial
   viewport</a> and the <a href="#actual-viewport">actual viewport</a>.

  <dl>
   <dt><dfn id=initial-viewport>initial viewport</dfn>

   <dd>This refers to the viewport before any UA or author styles have
    overridden the viewport given by the window or viewing area of the UA.
    Note that the initial viewport size will change with the size of the
    window or viewing area.

   <dt><dfn id=actual-viewport>actual viewport</dfn>

   <dd>This is the viewport you get after the cascaded viewport properties,
    and the following <a href="#constraining-procedure">constraining
    procedure</a> have been applied.
  </dl>

  <p>When the <a href="#actual-viewport">actual viewport</a> cannot fit
   inside the window or viewing area, either because the <a
   href="#actual-viewport">actual viewport</a> is larger than the <a
   href="#initial-viewport">initial viewport</a> or the zoom factor causes
   only parts of the <a href="#actual-viewport">actual viewport</a> to be
   visible, the UA should offer a scrolling or panning mechanism.

  <p>It is recommended that initially the upper-left corners of the <a
   href="#actual-viewport"> actual viewport</a> and the window or viewing
   area are aligned if the base direction of the document is ltr. Similarly,
   that the upper-right corners are aligned when the base direction is rtl.
   The base direction for a document is defined as the computed value of the
   <code class=property>direction</code> property for the first <code
   class=html>BODY</code> element of an HTML or XHTML document. For other
   document types, it is the computed <code class=property>direction</code>
   for the root element.

  <p class=issue>"dbaron: The question is, what does this do on the desktop
   browser? (And what's a desktop browser)". Need to say that a "desktop"
   browser typically have no UA styles, as opposed to the <a
   href="#ua-stylesheet">UA stylesheet</a> outlined for current mobile
   behaviour, and that no UA styles for @viewport will give "desktop"
   behaviour per default (actual viewport is initial viewport).

  <h2 id=the-viewport-rule><span class=secno>4. </span>The <code
   class=css>@viewport</code> rule</h2>

  <p>The <code class=css>@viewport</code> <a
   href="http://www.w3.org/TR/CSS21/syndata.html#at-rules">at-rule</a>
   consists of the @-keyword followed by a block of property declarations
   describing the viewport.

  <p>The property declarations inside an <code class=css>@viewport</code>
   rule are per document properties and there is no inheritance involved.
   Hence declarations using the &lsquo;<code class=css>inherit</code>&rsquo;
   keyword will be dropped. They work similar to <code class=css>@page</code>
   properties and follow the cascading order of CSS. Hence, properties in
   <code class=css>@viewport</code> rules will override properties from
   preceding rules. The declarations allow !important which will affect
   cascading of properties accordingly.

  <p class=issue>Should the @viewport rule apply to top-level documents only?
   If not, we need to say something about different zoom factors in frames.

  <p class=issue>Bert: What's interactions of @viewport and @page

  <div class=example>
   <p>This example sets the viewport to fit the width of the device. Note
    that it is enough to set the width as the height will be resolved from
    the width.</p>

   <pre><!--
	-->@viewport {
<!--    -->  width: device-width;
<!--    -->}<!--
   --></pre>
  </div>

  <h3 id=syntax><span class=secno>4.1. </span>Syntax</h3>

  <p>The syntax for the <code class=css>@viewport</code> rule is as follows
   (using the notation from the <a
   href="http://www.w3.org/TR/CSS21/grammar.html">Grammar appendix</a> of CSS
   2.1 <a href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>):

  <pre><!--
    -->viewport
<!---->  : VIEWPORT_SYM S*
<!---->    '{' S* declaration? [ ';' S* declaration? ]* '}' S*<!--
      -->;</pre>

  <p>with the new token:

  <pre>@{V}{I}{E}{W}{P}{O}{R}{T} {return VIEWPORT_SYM;}</pre>

  <p> where:

  <pre>V               v|\\0{0,4}(56|76)(\r\n|[ \t\r\n\f])?|\\v
<!--  -->W               w|\\0{0,4}(57|77)(\r\n|[ \t\r\n\f])?|\\w</pre>

  <p>The <code>viewport</code> non-terminal is added to the
   <code>stylesheet</code> production along with the <code>ruleset</code>,
   <code>media</code>, and <code>page</code> non-terminals:

  <pre><!--
      -->stylesheet
<!--  -->  : [ CHARSET_SYM STRING ';' ]?
<!--  -->    [S|CDO|CDC]* [ import [ CDO S* | CDC S* ]* ]*
<!--  -->    [ [ ruleset | media | page | viewport ] [ CDO S* | CDC S* ]* ]*
<!--  -->  ;<!--
 --></pre>

  <p>It is also added to media production to allow <code
   class=css>@viewport</code> rules nested inside <code
   class=css>@media</code> rules <span class=note>This is extending the CSS
   2.1 syntax. A draft of CSS3 Paged Media also allows page inside
   @media.</span>:

  <pre><!--
      -->media
<!--  -->  : MEDIA_SYM S* media_list LBRACE S* [ ruleset | viewport ]* '}' S*
<!--  -->  ;<!--
 --></pre>

  <h2 id=viewport-properties><span class=secno>5. </span>Viewport properties</h2>

  <p>This section presents the properties that are allowed inside an <code
   class=css>@viewport</code> rule. Other properties than those listed here
   will be dropped.

  <p>Relative length values are resolved against initial values. For instance
   &lsquo;<code class=property>em</code>&rsquo;s are resolved against the
   initial value of the font-size property.

  <h3 id=the-lsquomin-widthrsquo-and-lsquomax-wid><span class=secno>5.1.
   </span>The &lsquo;<a href="#min-width"><code
   class=property>min-width</code></a>&rsquo; and &lsquo;<a
   href="#max-width"><code class=property>max-width</code></a>&rsquo;
   properties</h3>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=min-width>min-width</dfn>

    <tr>
     <td><em>Value:</em>

     <td><a href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a>

    <tr>
     <td><em>Initial:</em>

     <td><a href="#auto" title="auto!!length">auto</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>Refer to the width of the <a href="#initial-viewport">initial
      viewport</a>

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#auto"><code class=css
      title="auto!!length">auto</code></a>&rsquo;, &lsquo;<a
      href="#device-width"><code class=css>device-width</code></a>&rsquo;,
      &lsquo;<a href="#device-height"><code
      class=css>device-height</code></a>&rsquo;, an absolute length, or a
      percentage as specified
  </table>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=max-width>max-width</dfn>

    <tr>
     <td><em>Value:</em>

     <td><a href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a>

    <tr>
     <td><em>Initial:</em>

     <td><a href="#auto" title="auto!!length">auto</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>Refer to the width of the <a href="#initial-viewport">initial
      viewport</a>

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#auto"><code class=css
      title="auto!!length">auto</code></a>&rsquo;, &lsquo;<a
      href="#device-width"><code class=css>device-width</code></a>&rsquo;,
      &lsquo;<a href="#device-height"><code
      class=css>device-height</code></a>&rsquo;, an absolute length, or a
      percentage as specified
  </table>

  <p>Specifies the minimum and maximum width of the <a
   href="http://www.w3.org/TR/CSS21/visuren.html#viewport">viewport</a> that
   is used to set the size of the <a
   href="http://www.w3.org/TR/CSS21/visudet.html#containing-block-details">
   initial containing block</a> where

  <p style="margin: 1em"><var><dfn
   id=ltviewport-lengthgt>&lt;viewport-length&gt;</dfn></var> = auto |
   device-width | device-height | <var>&lt;length&gt;</var> |
   <var>&lt;percentage&gt;</var>

  <p>and the values have the following meanings:

  <dl>
   <dt>&lsquo;<code class=css><dfn id=auto
    title="auto!!length">auto</dfn></code>&rsquo;

   <dd>The used value is calculated from the other property values according
    to the <a href="#constraining-procedure">constraining procedure</a>.

   <dt>&lsquo;<code class=css><dfn
    id=device-width>device-width</dfn></code>&rsquo;

   <dd>The width of the screen in CSS pixels at zoom factor 1.0.

   <dt>&lsquo;<code class=css><dfn
    id=device-height>device-height</dfn></code>&rsquo;

   <dd>The height of the screen in CSS pixels at zoom factor 1.0.

   <dt><var>&lt;length&gt;</var>

   <dd>
    <p>A positive absolute or relative length.</p>

   <dt><var>&lt;percentage&gt;</var>

   <dd>
    <p>A percentage value relative to the width or height of the <a
     href="#initial-viewport">initial viewport</a> at zoom factor 1.0, for
     horizontal and vertical lengths respectively. Must be positive.</p>
  </dl>

  <p>The min-width and max-width properties are inputs to the <a
   href="#constraining-procedure">constraining procedure</a>. The width will
   initially be set as close as possible to the <a
   href="#initial-viewport">initial viewport</a> width within the min/max
   constraints.

  <h3 id=the-lsquowidthrsquo-shorthand-property><span class=secno>5.2.
   </span>The &lsquo;<a href="#width"><code
   class=property>width</code></a>&rsquo; shorthand property</h3>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=width>width</dfn>

    <tr>
     <td><em>Value:</em>

     <td><a href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a>{1,2}

    <tr>
     <td><em>Initial:</em>

     <td>See individual properties

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>See individual properties

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>See individual properties
  </table>

  <p>This is a shorthand property for setting both min-width and max-width.
   One <a href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a> value will
   set both min-width and max-width to that value. Two <a
   href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a> values will set
   min-width to the first and max-width to the second.

  <h3 id=the-lsquomin-heightrsquo-and-lsquomax-he><span class=secno>5.3.
   </span>The &lsquo;<a href="#min-height"><code
   class=property>min-height</code></a>&rsquo; and &lsquo;<a
   href="#max-height"><code class=property>max-height</code></a>&rsquo;
   properties</h3>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=min-height>min-height</dfn>

    <tr>
     <td><em>Value:</em>

     <td><a href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a>

    <tr>
     <td><em>Initial:</em>

     <td><a href="#auto" title="auto!!length">auto</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>Refer to the height of the <a href="#initial-viewport">initial
      viewport</a>

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#auto"><code class=css
      title="auto!!length">auto</code></a>&rsquo;, &lsquo;<a
      href="#device-width"><code class=css>device-width</code></a>&rsquo;,
      &lsquo;<a href="#device-height"><code
      class=css>device-height</code></a>&rsquo;, an absolute length, or a
      percentage as specified
  </table>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=max-height>max-height</dfn>

    <tr>
     <td><em>Value:</em>

     <td><a href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a>

    <tr>
     <td><em>Initial:</em>

     <td><a href="#auto" title="auto!!length">auto</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>Refer to the height of the <a href="#initial-viewport">initial
      viewport</a>

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#auto"><code class=css
      title="auto!!length">auto</code></a>&rsquo;, &lsquo;<a
      href="#device-width"><code class=css>device-width</code></a>&rsquo;,
      &lsquo;<a href="#device-height"><code
      class=css>device-height</code></a>&rsquo;, an absolute length, or a
      percentage as specified
  </table>

  <p>Specifies the minimum and maximum height of the <a
   href="http://www.w3.org/TR/CSS21/visuren.html#viewport">viewport</a> that
   is used to set the size of the <a
   href="http://www.w3.org/TR/CSS21/visudet.html#containing-block-details">
   initial containing block</a>.

  <p>The min-height and max-height properties are inputs to the <a
   href="#constraining-procedure">constraining procedure</a>. The height will
   initially be set as close as possible to the <a
   href="#initial-viewport">initial viewport</a> height within the min/max
   constraints.

  <h3 id=the-lsquoheightrsquo-shorthand-property><span class=secno>5.4.
   </span>The &lsquo;<a href="#height"><code
   class=property>height</code></a>&rsquo; shorthand property</h3>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=height>height</dfn>

    <tr>
     <td><em>Value:</em>

     <td><a href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a>{1,2}

    <tr>
     <td><em>Initial:</em>

     <td>See individual properties

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>See individual properties

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>See individual properties
  </table>

  <p>This is a shorthand property for setting both min-height and max-height.
   One <a href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a> value will
   set both min-height and max-height to that value. Two <a
   href="#ltviewport-lengthgt">&lt;viewport-length&gt;</a> values will set
   min-height to the first and max-height to the second.

  <h3 id=the-lsquozoomrsquo-property><span class=secno>5.5. </span>The
   &lsquo;<a href="#zoom"><code class=property
   title="zoom!!property">zoom</code></a>&rsquo; property</h3>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=zoom title="zoom!!property">zoom</dfn>

    <tr>
     <td><em>Value:</em>

     <td>auto | &lt;number&gt; | &lt;percentage&gt;

    <tr>
     <td><em>Initial:</em>

     <td><a href="#auto0" title="auto!!zoom">auto</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>The zoom factor itself

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#auto0"><code class=css
      title="auto!!zoom">auto</code></a>&rsquo;, or a positive number or
      percentage as specified.
  </table>

  <p>Specifies the initial zoom factor for the window or viewing area. This
   is a magnifying glass type of zoom. Interactively changing the zoom factor
   from the initial zoom factor does not affect the size of the initial or
   the actual viewport.

  <p>Values have the following meanings: <span class=issue>Should both
   numbers and percentages be
   allowed?<!-- http://lists.w3.org/Archives/Public/www-style/2010Oct/0321.html --></span>

  <dl>
   <dt>&lsquo;<code class=css><dfn id=auto0
    title="auto!!zoom">auto</dfn></code>&rsquo;

   <dd>The zoom factor is UA-dependent. The UA may use the size of the area
    of the canvas on which the document is rendered to find that initial zoom
    factor. See <a href="#handling-auto-zoom">this section</a> for a proposed
    way of handling &lsquo;<a href="#auto0"><code class=css
    title="auto!!zoom">auto</code></a>&rsquo; values for &lsquo;<a
    href="#zoom"><code class=property
    title="zoom!!property">zoom</code></a>&rsquo;.

   <dt><var>&lt;number&gt;</var>

   <dd>
    <p>A positive number used as a zoom factor. A factor of 1.0 means that no
     zooming is done. Values larger than 1.0 gives a zoomed-in effect and
     values smaller than 1.0 a zoomed-out effect.</p>

   <dt><var>&lt;percentage&gt;</var>

   <dd>
    <p>A positive percentage value used as a zoom factor. A factor of 100%
     means that no zooming is done. Values larger than 100% gives a zoomed-in
     effect and values smaller than 100% a zoomed-out effect.</p>
  </dl>

  <h3 id=the-lsquomin-zoomrsquo-property><span class=secno>5.6. </span>The
   &lsquo;<a href="#min-zoom"><code class=property>min-zoom</code></a>&rsquo;
   property</h3>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=min-zoom>min-zoom</dfn>

    <tr>
     <td><em>Value:</em>

     <td>auto | &lt;number&gt; | &lt;percentage&gt;

    <tr>
     <td><em>Initial:</em>

     <td><a href="#auto1" title="auto!!min-zoom">auto</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>The zoom factor itself

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#auto1"><code class=css
      title="auto!!min-zoom">auto</code></a>&rsquo;, or a positive number or
      percentage as specified.
  </table>

  <p>Specifies the smallest allowed zoom factor. It is used as input to the
   <a href="#constraining-procedure">constraining procedure</a> to constrain
   non-&lsquo;<a href="#auto0"><code class=css
   title="auto!!zoom">auto</code></a>&rsquo; &lsquo;<a href="#zoom"><code
   class=property title="zoom!!property">zoom</code></a>&rsquo; values, but
   also to limit the allowed zoom factor that can be set through user
   interaction. The UA should also use this value as a constraint when
   choosing an actual zoom factor when the used value of &lsquo;<a
   href="#zoom"><code class=property
   title="zoom!!property">zoom</code></a>&rsquo; is &lsquo;<a
   href="#auto0"><code class=css title="auto!!zoom">auto</code></a>&rsquo;.

  <p>Values have the following meanings:

  <dl>
   <dt>&lsquo;<code class=css><dfn id=auto1
    title="auto!!min-zoom">auto</dfn></code>&rsquo;

   <dd>The lower limit on zoom factor is UA dependant. There will be no
    minimum value constraint on the &lsquo;<a href="#zoom"><code
    class=property title="zoom!!property">zoom</code></a>&rsquo; property
    used in the <a href="#constraining-procedure">constraining procedure</a>

   <dt><var>&lt;number&gt;</var>

   <dd>
    <p>A positive number limiting the minimum value of the zoom factor.</p>

   <dt><var>&lt;percentage&gt;</var>

   <dd>
    <p>A positive percentage limiting the minimum value of the zoom factor.</p>
  </dl>

  <h3 id=the-lsquomax-zoomrsquo-property><span class=secno>5.7. </span>The
   &lsquo;<a href="#max-zoom"><code class=property>max-zoom</code></a>&rsquo;
   property</h3>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=max-zoom>max-zoom</dfn>

    <tr>
     <td><em>Value:</em>

     <td>auto | &lt;number&gt; | &lt;percentage&gt;

    <tr>
     <td><em>Initial:</em>

     <td><a href="#auto2" title="auto!!max-zoom">auto</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>The zoom factor itself

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#auto2"><code class=css
      title="auto!!max-zoom">auto</code></a>&rsquo;, or a positive number or
      percentage as specified.
  </table>

  <p>Specifies the largest allowed zoom factor. It is used as input to the <a
   href="#constraining-procedure">constraining procedure</a> to constrain
   non-&lsquo;<a href="#auto0"><code class=css
   title="auto!!zoom">auto</code></a>&rsquo; &lsquo;<a href="#zoom"><code
   class=property title="zoom!!property">zoom</code></a>&rsquo; values, but
   also to limit the allowed zoom factor that can be set through user
   interaction. The UA should also use this value as a constraint when
   choosing an actual zoom factor when the used value of &lsquo;<a
   href="#zoom"><code class=property
   title="zoom!!property">zoom</code></a>&rsquo; is &lsquo;<a
   href="#auto0"><code class=css title="auto!!zoom">auto</code></a>&rsquo;.

  <p>Values have the following meanings:

  <dl>
   <dt>&lsquo;<code class=css><dfn id=auto2
    title="auto!!max-zoom">auto</dfn></code>&rsquo;

   <dd>The upper limit on zoom factor is UA dependant. There will be no
    maximum value constraint on the &lsquo;<code
    class=property>zoom</code>&rsquo; property used in the <a
    href="#constraining-procedure">constraining procedure</a>

   <dt><var>&lt;number&gt;</var>

   <dd>
    <p>A positive number limiting the maximum value of the zoom factor.</p>

   <dt><var>&lt;percentage&gt;</var>

   <dd>
    <p>A positive percentage limiting the maximum value of the zoom factor.</p>
  </dl>

  <h3 id=the-lsquouser-zoomrsquo-property><span class=secno>5.8. </span>The
   &lsquo;<a href="#user-zoom"><code
   class=property>user-zoom</code></a>&rsquo; property</h3>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=user-zoom>user-zoom</dfn>

    <tr>
     <td><em>Value:</em>

     <td>zoom | fixed

    <tr>
     <td><em>Initial:</em>

     <td><a href="#zoom0" title="zoom!!value">zoom</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>N/A

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#zoom0"><code class=css
      title="zoom!!value">zoom</code></a>&rsquo; or &lsquo;<a
      href="#fixed"><code class=css>fixed</code></a>&rsquo; as specified.
  </table>

  <p>Specifies if the zoom factor can be changed by user interaction or not.

  <p>Values have the following meanings:

  <dl>
   <dt>&lsquo;<code class=css><dfn id=zoom0
    title="zoom!!value">zoom</dfn></code>&rsquo;

   <dd>The user can interactively change the zoom factor.

   <dt>&lsquo;<code class=css><dfn id=fixed>fixed</dfn></code>&rsquo;

   <dd>The user cannot interactively change the zoom factor.
  </dl>

  <h3 id=the-lsquoorientationrsquo-property><span class=secno>5.9. </span>The
   &lsquo;<a href="#orientation"><code
   class=property>orientation</code></a>&rsquo; property</h3>

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=orientation>orientation</dfn>

    <tr>
     <td><em>Value:</em>

     <td>auto | portrait | landscape

    <tr>
     <td><em>Initial:</em>

     <td><a href="#auto3" title="auto!!orientation">auto</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>N/A

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#auto3"><code class=css
      title="auto!!orientation">auto</code></a>&rsquo;, &lsquo;<a
      href="#portrait"><code class=css>portrait</code></a>&rsquo;, or
      &lsquo;<a href="#landscape"><code class=css>landscape</code></a>&rsquo;
      as specified.
  </table>

  <p>This property is used to request that a document is displayed in
   portrait or landscape mode. For a UA/device where the orientation is
   changed upon tilting the device, an author can use this property to
   inhibit the orientation change.

  <p>Values have the following meanings:

  <dl>
   <dt>&lsquo;<code class=css><dfn id=auto3
    title="auto!!orientation">auto</dfn></code>&rsquo;

   <dd>The UA automatically chooses the orientation based on the device's
    normal mode of operation. The UA may choose to change the orientation of
    the presentation when the device is tilted.

   <dt>&lsquo;<code class=css><dfn id=portrait>portrait</dfn></code>&rsquo;

   <dd>The document should be locked to portrait presentation.

   <dt>&lsquo;<code class=css><dfn id=landscape>landscape</dfn></code>&rsquo;

   <dd>The document should be locked to landscape presentation.
  </dl>

  <h3 id=the-lsquoresolutionrsquo-property><span class=secno>5.10. </span>The
   &lsquo;<a href="#resolution"><code
   class=property>resolution</code></a>&rsquo; property</h3>

  <p class=issue>This property is at risk.</p>
  <!-- http://lists.w3.org/Archives/Public/www-style/2010Aug/0131.html -->

  <table class=propdef>
   <tbody>
    <tr>
     <td><em>Name:</em>

     <td><dfn id=resolution>resolution</dfn>

    <tr>
     <td><em>Value:</em>

     <td>auto | device | &lt;resolution&gt;

    <tr>
     <td><em>Initial:</em>

     <td><a href="#auto4" title="auto!!resolution">auto</a>

    <tr>
     <td><em>Applies to:</em>

     <td>N/A

    <tr>
     <td><em>Inherited:</em>

     <td>N/A

    <tr>
     <td><em>Percentages:</em>

     <td>N/A

    <tr>
     <td><em>Media:</em>

     <td>visual, continuous

    <tr>
     <td><em>Computed&nbsp;value:</em>

     <td>&lsquo;<a href="#auto4"><code class=css
      title="auto!!resolution">auto</code></a>&rsquo;, &lsquo;<a
      href="#device"><code class=css>device</code></a>&rsquo;, or a
      resolution value as specified.
  </table>

  <p>The UA relates the CSS pixel to the <a
   href="http://www.w3.org/TR/CSS21/syndata.html#x40">reference pixel</a> or
   the physical <a
   href="http://www.w3.org/TR/CSS21/syndata.html#length-units">length
   units</a> as described in CSS 2.1 <a href="#CSS21"
   rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>. The resolution property can
   be used to override the CSS pixel size chosen by the UA by setting a CSS
   pixel resolution. In CSS, absolute length units are fixed in relation to
   each other, hence, changing the CSS pixel resolution will for instance
   change the physical length of a CSS cm.

  <p>The relationship between a device pixel and a CSS pixel will depend on
   the device resolution. Setting <code>resolution: 120dpi</code> on a 240dpi
   device will give a 2:1 ratio between device and CSS pixels, while on a
   120dpi device, the ratio will be 1:1. Likewise, the &lsquo;<a
   href="#device"><code class=css>device</code></a>&rsquo; value will always
   keep a 1:1 ratio, but will give different CSS pixel resolution depending
   on device resolution.

  <p>Note that setting this property will affect the used lengths for
   &lsquo;<a href="#device-width"><code
   class=css>device-width</code></a>&rsquo;, &lsquo;<a
   href="#device-height"><code class=css>device-height</code></a>&rsquo;, and
   the size of the <a href="#initial-viewport">initial viewport</a>.

  <p>The <dfn id=ltresolutiongt>&lt;resolution&gt;</dfn> value is a positive
   &lt;number&gt immediately followed by a unit identifier (&lsquo;<code
   class=css>dpi</code>&rsquo; or &lsquo;<code class=css>dpcm</code>&rsquo;).

  <p>Values have the following meanings:

  <dl>
   <dt>&lsquo;<code class=css><dfn id=auto4
    title="auto!!resolution">auto</dfn></code>&rsquo;

   <dd>Use the UAs CSS pixel resolution.

   <dt>&lsquo;<code class=css><dfn id=device>device</dfn></code>&rsquo;

   <dd>Use device resolution as the CSS pixel resolution. That is, have a 1-1
    relationship between a CSS and a device pixel.

   <dt><a href="#ltresolutiongt"><var>&lt;resolution&gt;</var></a>

   <dd>Set the CSS pixel resolution to a fixed dpi or dpcm value.
  </dl>

  <h2 id=constraining-viewport-property-values><span class=secno>6.
   </span>Constraining viewport property values</h2>

  <h3 id=definitions><span class=secno>6.1. </span>Definitions</h3>

  <p>For the procedure below:

  <p>Properties refer to the values resolved/constrained to at that point in
   the procedure. They are initially resolved to their computed values.

  <p><code class=index id=width0 title="width!!resolved">width</code> and
   <code class=index id=height0 title="height!!resolved">height</code> refer
   to the resolved viewport size and not the shorthand properties. They are
   both initially &lsquo;<a href="#auto"><code class=css
   title="auto!!length">auto</code></a>&rsquo;.

  <p> <code>MIN/MAX</code> computations where one of the arguments is
   &lsquo;<code class=css>auto</code>&rsquo; resolve to the other argument.
   For instance, <code>MIN(0.25, 'auto') = 0.25</code>, and <code>MAX(5,
   'auto') = 5</code>.

  <p> <code class=index id=initial-width
   title="width!!initial">initial-width</code> is the width of the <a
   href="#initial-viewport">initial viewport</a> in pixels at zoom factor
   1.0.

  <p> <code class=index id=initial-height
   title="height!!initial">initial-height</code> is the height of the <a
   href="#initial-viewport">initial viewport</a> in pixels at zoom factor
   1.0.

  <h3 id=constraining-procedure><span class=secno>6.2. </span>The procedure</h3>

  <p>The used values are resolved from the computed values going through the
   steps below.

  <p>User agents are expected, but not required, to re-run this procedure and
   re-layout the document, if necessary, in response to changes in the user
   environment, for example if the device is tilted from landscape to
   portrait mode or the window that forms the <a
   href="#initial-viewport">initial viewport</a> is resized.

  <h4 class="no-num no-toc"
   id=resolve-non-lsquoautorsquo-lengths-to-pi>Resolve non-&lsquo;<a
   href="#auto"><code class=css title="auto!!length">auto</code></a>&rsquo;
   lengths to pixel lengths</h4>

  <ol>
   <li>Resolve relative and absolute lengths, percentages, and keywords
    (&lsquo;<a href="#device-width"><code
    class=css>device-width</code></a>&rsquo;, &lsquo;<a
    href="#device-height"><code class=css>device-height</code></a>&rsquo;) to
    pixel values for the &lsquo;<a href="#min-width"><code
    class=property>min-width</code></a>&rsquo;, &lsquo;<a
    href="#max-width"><code class=property>max-width</code></a>&rsquo;,
    &lsquo;<a href="#min-height"><code
    class=property>min-height</code></a>&rsquo; and &lsquo;<a
    href="#max-height"><code class=property>max-height</code></a>&rsquo;
    properties
  </ol>

  <h4 class="no-num no-toc"
   id=resolve-initial-width-and-height-from-mi>Resolve initial <code
   title="width!!resolved">width</code> and <code
   title="height!!resolved">height</code> from min/max properties</h4>

  <ol id=ol2>
   <li>If <code title="min-width!!resolved">min-width</code> or <code
    title="max-width!!resolved">max-width</code> is not &lsquo;<a
    href="#auto"><code class=css title="auto!!length">auto</code></a>&rsquo;,
    set <code>width = MAX(min-width, MIN(max-width, initial-width))</code>

   <li>If <code title="min-height!!resolved">min-height</code> or <code
    title="max-height!!resolved">max-height</code> is not &lsquo;<a
    href="#auto"><code class=css title="auto!!length">auto</code></a>&rsquo;,
    set <code>height = MAX(min-height, MIN(max-height,
    initial-height))</code>
  </ol>

  <h4 class="no-num no-toc" id=resolve-min-zoom-and-max-zoom-values>Resolve
   <code title="min-zoom!!resolved">min-zoom</code> and <code
   title="max-zoom!!resolved">max-zoom</code> values</h4>

  <ol id=ol4>
   <li>If <code title="min-zoom!!resolved">min-zoom</code> is not &lsquo;<a
    href="#auto1"><code class=css
    title="auto!!min-zoom">auto</code></a>&rsquo; and <code
    title="max-zoom!!resolved">max-zoom</code> is not &lsquo;<a
    href="#auto2"><code class=css
    title="auto!!max-zoom">auto</code></a>&rsquo;, set <code>max-zoom =
    MAX(min-zoom, max-zoom)</code>
  </ol>

  <h4 class="no-num no-toc"
   id=constrain-zoom-value-to-the-min-zoom-max>Constrain <code
   title="zoom!!resolved">zoom</code> value to the <code>[min-zoom,
   max-zoom]</code> range</h4>

  <ol id=ol5>
   <li>If <code title="zoom!!resolved">zoom</code> is not &lsquo;<a
    href="#auto0"><code class=css title="auto!!zoom">auto</code></a>&rsquo;,
    set <code>zoom = MAX(min-zoom, MIN(max-zoom, zoom))</code>
  </ol>

  <h4 class="no-num no-toc" id=resolve-width-value>Resolve <code
   title="width!!resolved">width</code> value</h4>

  <ol id=ol6>
   <li>If <code title="width!!resolved">width</code> and <code
    title="zoom!!resolved">zoom</code> are both &lsquo;<code
    class=css>auto</code>&rsquo;, set <code>width = initial-width</code>

   <li>If <code title="width!!resolved">width</code> is &lsquo;<code
    class=css>auto</code>&rsquo;, and <code
    title="height!!resolved">height</code> is &lsquo;<code
    class=css>auto</code>&rsquo;, set <code>width = (initial-width /
    zoom)</code>

   <li>If <code title="width!!resolved">width</code> is &lsquo;<code
    class=css>auto</code>&rsquo;, set <code>width = height * (initial-width /
    initial-height)</code>
  </ol>

  <h4 class="no-num no-toc" id=resolve-height-value>Resolve <code
   title="height!!resolved">height</code> value</h4>

  <ol id=ol9>
   <li>If <code title="height!!resolved">height</code> is &lsquo;<code
    class=css>auto</code>&rsquo;, set <code>height = width * (initial-height
    / initial-width)</code>
  </ol>

  <h4 class="no-num no-toc"
   id=extend-width-and-height-to-fill-the-wind>Extend <code
   title="width!!resolved">width</code> and <code
   title="height!!resolved">height</code> to fill the window/viewing area for
   the specified <code title="zoom!!resolved">zoom</code></h4>

  <ol id=ol10>
   <li>If <code title="zoom!!resolved">zoom</code> or <code
    title="max-zoom!!resolved">max-zoom</code> is not &lsquo;<a
    href="#auto0"><code class=css title="auto!!zoom">auto</code></a>&rsquo;,
    set <code>width = MAX(width, (initial-width / MIN(zoom,
    max-zoom)))</code>

   <li>If <code title="zoom!!resolved">zoom</code> or <code
    title="max-zoom!!resolved">max-zoom</code> is not &lsquo;<a
    href="#auto0"><code class=css title="auto!!zoom">auto</code></a>&rsquo;,
    set <code>height = MAX(height, (initial-height / MIN(zoom,
    max-zoom)))</code>
  </ol>

  <div class=example>
   <p>This example shows the case where the used value for width is increased
    to fit the window/viewing area for a specified zoom value. The used value
    for width will be two times device-width in this case, assuming
    device-width is the same as the <a href="#initial-viewport">initial
    viewport</a> width.</p>

   <pre><!--
	  -->@viewport {
<!--	  -->  width: device-width;
<!--	  -->  zoom: 0.5;
<!--      -->}<!--
     --></pre>
  </div>

  <h2 id=media-queries><span class=secno>7. </span>Media Queries</h2>

  <p>For several media features, the size of the initial containing block and
   the orientation of the device affects the result of a media query
   evaluation, which means that the effect of <code
   class=css>@viewport</code> rules on media queries needs extra attention.

  <p class=issue>Bert: If you put @viewport, can you put @viewport in @media?
   Say what it means?

  <p>From the Media Queries specification <a href="#MEDIAQ"
   rel=biblioentry>[MEDIAQ]<!--{{!MEDIAQ}}--></a>:

  <blockquote>
   <p>&ldquo;To avoid circular dependencies, it is never necessary to apply
    the style sheet in order to evaluate expressions. For example, the aspect
    ratio of a printed document may be influenced by a style sheet, but
    expressions involving &lsquo;device-aspect-ratio&rsquo; will be based on
    the default aspect ratio of the user agent.&rdquo;
  </blockquote>

  <p>For <code class=css>@viewport</code> rules, though, it is recommended
   that they are applied before media queries for other rules are evaluated.

  <p>Recommended procedure for applying CSS rules:

  <ol>
   <li>Apply <code class=css>@viewport</code> rules. If <code
    class=css>@viewport</code> rules rely on media queries, use the viewport
    properties of the <a href="#initial-viewport">initial viewport</a>.

   <li>Apply style rules. If style rules rely on media queries, use the
    viewport properties obtained from step 1 when evaluating the media
    queries.
  </ol>

  <p class=note>The rationale for using the viewport properties obtained from
   applying the <code class=css>@viewport</code> rules for evaluating media
   queries for style rules, is that media queries should match the <a
   href="#actual-viewport">actual viewport</a> that the document will be
   layed out in and not the initial or the one specified in the UA
   stylesheet. Consider the example below given that the UA stylesheet has a
   viewport width of 980px, but a device-width and <a
   href="#initial-viewport">initial viewport</a> width of 320px. The author
   has made separate styles to make the document look good for initial
   containing block widths above or below 400px. The <a
   href="#actual-viewport">actual viewport</a> used will be 320px wide, and
   in order to match the styles with the <a href="#actual-viewport">actual
   viewport</a> width, the viewport resulting from applying the <code
   class=css>@viewport</code> rules should be used to evaluate the media
   queries.

  <div class=example>
   <p>Given a device-width of 320px and a UA stylesheet viewport width of
    980px, the first media query will not match, but the second will.</p>

   <pre><!--
	-->@viewport {
<!--    -->  width: device-width;
<!--    -->}
<!--    -->
<!--    -->@media screen and (min-width: 400px) {
<!--    -->  div { color: red; }
<!--    -->}
<!--    -->
<!--    -->@media screen and (max-width: 400px) {
<!--    -->  div { color: green; }
<!--    -->}<!--
   --></pre>
  </div>

  <p>Another example:

  <div class=example>
   <p>The media query below should match because the <code
    class=css>@viewport</code> rule is applied before the media query is
    evaluated.</p>

   <pre><!--
	-->@media screen and (width: 397px) {
<!--    -->  div { color: green; }
<!--    -->}
<!--    -->
<!--    -->@viewport {
<!--    -->  width: 397px;
<!--    -->}<!--
   --></pre>
  </div>

  <p>Below is an example where an <code class=css>@viewport</code> rule
   relies on a media query affected by the viewport properties.

  <div class=example>
   <p>The green color should be applied to a div because the <a
    href="#initial-viewport">initial viewport</a> width is used to evaluate
    the media query for the second <code class=css>@viewport</code> rule, but
    the <a href="#actual-viewport">actual viewport</a> is used for evaluating
    the media query when applying style rules.</p>

   <pre><!--
        -->@viewport {
<!--    -->  width: 397px;
<!--    -->}
<!--    -->
<!--    -->@media screen and (width: 397px) {
<!--    -->  @viewport {
<!--    -->    width: 500px;
<!--    -->  }
<!--    -->}
<!--    -->
<!--    -->@media screen and (width: 397px) {
<!--    -->  div { color: green; }
<!--    -->}<!--
   --></pre>
  </div>

  <p>It is recommended that authors do not write <code
   class=css>@viewport</code> rules that rely on media queries whose
   evaluation is affected by viewport properties. Is is also recommended that
   the <code class=css>@viewport</code> rule(s) is placed as early in the
   document as possible to avoid unnecessary re-evaluation of media queries
   or reflows.

  <p>The next example illustrates possible circular dependencies between
   media queries and <code class=css>@viewport</code> rules. Assuming a UA
   stylesheet viewport width larger than 200px, the first viewport rule would
   apply causing an <a href="#actual-viewport">actual viewport</a> width of
   100px. If the media queries were based on the <a
   href="#actual-viewport">actual viewport</a>, a re-evaluation would apply
   the second <code class=css>@viewport</code> rule which would in turn cause
   the first media query to be true, which means we're back to start.

  <div class=example>
   <pre><!--
        -->@media screen and (min-width: 200px) {
<!--    -->  @viewport {
<!--    -->    width: 100px;
<!--    -->  }
<!--    -->}
<!--    -->
<!--    -->@media screen and (max-width: 200px) {
<!--    -->  @viewport {
<!--    -->    width: 300px;
<!--    -->  }
<!--    -->}<!--
   --></pre>
  </div>

  <p class=issue>There are prefixed implementations of a media feature for
   the device:css pixel ratio (-webkit-device-pixel-ratio /
   -o-device-pixel-ratio). Should be standardized here or in a new level of
   Media Queries?

  <h2 id=cssom><span class=secno>8. </span>CSSOM</h2>

  <p class=issue>Properties in the CSSOM and CSSOM View specifications refer
   to the <span>viewport</span> and the <span>initial containing
   block</span>. If any of those properties should refer to the <a
   href="#initial-viewport">initial viewport</a> and not the <a
   href="#actual-viewport">actual viewport</a>, those exceptions need to be
   adressed.

  <p class=issue>Standardize window.devicePixelRatio? Should be done in the
   CSSOM View spec perhaps?

  <h2 id=conformance><span class=secno>9. </span>Conformance</h2>

  <p>Requirements for a conforming UA:

  <ul>
   <li>
    <p>The &lsquo;<a href="#min-width"><code
     class=property>min-width</code></a>&rsquo;, &lsquo;<a
     href="#max-width"><code class=property>max-width</code></a>&rsquo;,
     &lsquo;<a href="#width"><code class=property>width</code></a>&rsquo;,
     &lsquo;<a href="#min-height"><code
     class=property>min-height</code></a>&rsquo;, &lsquo;<a
     href="#max-height"><code class=property>max-height</code></a>&rsquo;,
     and &lsquo;<a href="#height"><code
     class=property>height</code></a>&rsquo; properties must be supported.

   <li>
    <p>The &lsquo;<a href="#min-zoom"><code
     class=property>min-zoom</code></a>&rsquo;, &lsquo;<a
     href="#max-zoom"><code class=property>max-zoom</code></a>&rsquo;, and
     &lsquo;<a href="#zoom"><code class=property
     title="zoom!!property">zoom</code></a>&rsquo; properties must be
     supported as input to the <a href="#constraining-procedure">constraining
     procedure</a>. However, the UA may choose to use a different zoom factor
     when presenting the document to the user, and use different minimum and
     maximum zoom limits for the user interaction.</p>

    <p>This will for instance allow UAs without zooming capabilities to
     conform and still have interoperable implementations when it comes to
     viewport dimensions. It will also allow the UA to choose a different
     zoom factor when content overflows the <a href="#actual-viewport">actual
     viewport</a>.

   <li>
    <p>Support for the &lsquo;<a href="#user-zoom"><code
     class=property>user-zoom</code></a>&rsquo; and &lsquo;<a
     href="#orientation"><code class=property>orientation</code></a>&rsquo;
     properties is optional.
  </ul>

  <p class=issue>Need to say something about the resolution property if it is
   kept.

  <h2 id=viewport-meta-element><span class=secno>10. </span>Viewport <code
   class=html>META</code> element</h2>

  <p><em>This section is not normative.</em>

  <p>This section describes a mapping from the content attribute of the
   viewport <code class=html>META</code> element, first implemented by Apple
   in the iPhone Safari browser, to the properties of the <code
   class=css>@viewport</code> rule described in this specification.

  <h3 id=ua-stylesheet><span class=secno>10.1. </span>UA stylesheet</h3>

  <p>In order to match the Safari implementation, the following parsing
   algorithm and translation rules rely on the UA stylesheet below.

  <pre><!--
      -->@viewport {
<!--  -->  width: 980px;
<!--  -->  min-zoom: 0.25;
<!--  -->  max-zoom: 5;
<!--  -->}<!--
 --></pre>

  <p class=note>Note that these values might not fit well with all UAs. For
   instance, with a min-zoom of 0.25 you will be able to fit the whole width
   of the document inside the window for widths up to 1280px on a 320px wide
   device like the iPhone, but only 960px if you have 240px display.

  <h3 id=meta-properties><span class=secno>10.2. </span>Properties</h3>

  <p>The recognized properties in the viewport <code class=html>META</code>
   element are:

  <ul>
   <li><code class=index id=width1 title="width!!viewport META">width</code>

   <li><code class=index id=height1 title="height!!viewport
    META">height</code>

   <li><code class=index id=initial-scale>initial-scale</code>

   <li><code class=index id=minimum-scale>minimum-scale</code>

   <li><code class=index id=maximum-scale>maximum-scale</code>

   <li><code class=index id=user-scalable>user-scalable</code>

   <li><code class=index id=target-densitydpi>target-densityDpi</code><span
    class=issue>At risk since &lsquo;<a href="#resolution"><code
    class=property>resolution</code></a>&rsquo; is at risk.</span>
  </ul>

  <h3 id=parsing-algorithm><span class=secno>10.3. </span>Parsing algorithm</h3>

  <p>Below is an algorithm for parsing the <code class=html>content</code>
   attribute of the <code class=html>META</code> tag produced from testing
   Safari on the iPhone. <span class=note id=tested-safari>The testing was
   done on an iPod touch running iPhone OS 4. The UA string of the browser:
   <code>"Mozilla/5.0 (iPod; U; CPU iPhone OS 4_0 like Mac OS X; en-us)
   AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8A293
   Safari/6531.22.7"</code>.</span> The pseudo code notation used is based on
   the notation used in <a href="#Algorithms"
   rel=biblioentry>[Algorithms]</a>. The white-space class contains the
   following characters (ascii):

  <ul>
   <li>Horizontal tab (0x09)

   <li>Line feed (0x0a)

   <li>Carriage return (0x0d)

   <li>Space (0x20)
  </ul>

  <pre class=algorithm><!--
    --><span class=method><span class=method-name>Parse-Content</span>(<span class=variable>S</span>)</span>
<!----><span class=statement><span class=variable>i</span> &larr; 1</span>
<!----><span class=statement><span class=keyword>while</span> <span class=variable>i</span> &le; <span class=op>length</span>[<span class=variable>S</span>]</span>
<!----><span class=statement>    <span class=keyword>do</span> <span class=keyword>while</span> <span class=variable>i</span> &le; <span class=op>length</span>[<span class=variable>S</span>] and <span class=variable>S</span>[<span class=variable>i</span>] in [white-space, ',', '=']</span>
<!----><span class=statement>        <span class=keyword>do</span> <span class=variable>i</span> &larr; <span class=variable>i</span> + 1</span>
<!----><span class=statement>    <span class=keyword>if</span> <span class=variable>i</span> &le; <span class=op>length</span>[<span class=variable>S</span>]</span>
<!----><span class=statement>        <span class=keyword>then</span> <span class=variable>i</span> &larr; <span class=method-name>Parse-Property</span>(<span class=variable>S</span>, <span class=variable>i</span>)</span>
<!---->
<!----><span class=method><span class=method-name>Parse-Property</span>(<span class=variable>S</span>, <span class=variable>i</span>)</span>
<!----><span class=statement><span class=variable>start</span> &larr; <span class=variable>i</span></span>
<!----><span class=statement><span class=keyword>while</span> <span class=variable>i</span> &le; <span class=op>length</span>[<span class=variable>S</span>] and <span class=variable>S</span>[<span class=variable>i</span>] <span class=keyword>not</span> in [white-space, ',', '=']</span>
<!----><span class=statement>    <span class=keyword>do</span> <span class=variable>i</span> &larr; <span class=variable>i</span> + 1</span>
<!----><span class=statement><span class=keyword>if</span> <span class=variable>i</span> &gt; <span class=op>length</span>[<span class=variable>S</span>] or <span class=variable>S</span>[<span class=variable>i</span>] = ','</span>
<!----><span class=statement>    <span class=keyword>then</span> <span class=keyword>return</span> <span class=variable>i</span></span>
<!----><span class=statement><span class=variable>property-name</span> &larr; <span class=variable>S</span>[<span class=variable>start</span> .. (<span class=variable>i</span> - 1)]</span>
<!----><span class=statement><span class=keyword>while</span> <span class=variable>i</span> &le; <span class=op>length</span>[<span class=variable>S</span>] and <span class=variable>S</span>[<span class=variable>i</span>] <span class=keyword>not</span> in [',', '=']</span>
<!----><span class=statement>    <span class=keyword>do</span> <span class=variable>i</span> &larr; <span class=variable>i</span> + 1</span>
<!----><span class=statement><span class=keyword>if</span> <span class=variable>i</span> &gt; <span class=op>length</span>[<span class=variable>S</span>] or <span class=variable>S</span>[<span class=variable>i</span>] = ','</span>
<!----><span class=statement>    <span class=keyword>then</span> <span class=keyword>return</span> <span class=variable>i</span></span>
<!----><span class=statement><span class=keyword>while</span> <span class=variable>i</span> &le; <span class=op>length</span>[<span class=variable>S</span>] and <span class=variable>S</span>[<span class=variable>i</span>] in [white-space, '=']</span>
<!----><span class=statement>    <span class=keyword>do</span> <span class=variable>i</span> &larr; <span class=variable>i</span> + 1</span>
<!----><span class=statement><span class=keyword>if</span> <span class=variable>i</span> &gt; <span class=op>length</span>[<span class=variable>S</span>] or <span class=variable>S</span>[<span class=variable>i</span>] = ','</span>
<!----><span class=statement>    <span class=keyword>then</span> <span class=keyword>return</span> <span class=variable>i</span></span>
<!----><span class=statement><span class=variable>start</span> &larr; <span class=variable>i</span></span>
<!----><span class=statement><span class=keyword>while</span> <span class=variable>i</span> &le; <span class=op>length</span>[<span class=variable>S</span>] and <span class=variable>S</span>[<span class=variable>i</span>] <span class=keyword>not</span> in [white-space, ',', '=']</span>
<!----><span class=statement>    <span class=keyword>do</span> <span class=variable>i</span> &larr; <span class=variable>i</span> + 1</span>
<!----><span class=statement><span class=variable>property-value</span> &larr; <span class=variable>S</span>[<span class=variable>start</span> .. (<span class=variable>i</span> - 1)]</span>
<!----><span class=statement><span class=method-name>Set-Property</span>(<span class=variable>property-name</span>, <span class=variable>property-value</span>)</span>
<!----><span class=statement><span class=keyword>return</span> <span class=variable>i</span></span><!--
 --></pre>

  <p> <span class=method-name>Set-Property</span> matches the <a
   href="#meta-properties">listed property names</a> case-insensitively. The
   <code class=variable>property-value</code> strings are interpreted as
   follows:

  <ol>
   <li>If a prefix of <code class=variable>property-value</code> can be
    converted to a number using <code>strtod</code>, the value will be that
    number. The remainder of the string is ignored.

   <li>If the value can not be converted to a number as described above, the
    whole <code class=variable>property-value</code> string will be matched
    with the following strings case-insensitively: <code class=index
    id=yes>yes</code>, <code class=index id=no>no</code>, <code class=index
    id=device-width0 title="device-width!!viewport META">device-width</code>,
    <code class=index id=device-height0 title="device-height!!viewport
    META">device-height</code>

   <li>If the string did not match any of the known strings, the value is
    unknown.
  </ol>

  <h3 id=translation-into-viewport-properties><span class=secno>10.4.
   </span>Translation into <code class=css>@viewport</code> properties</h3>

  <p>The Viewport <code class=html>META</code> element is placed in the
   cascade as if it was a <code class=html>STYLE</code> element, in the exact
   same place in the dom, that only contains a single <code
   class=css>@viewport</code> rule.

  <p>Each of the property/value pair from the parsing in the previous section
   are translated, and added to that single at-rule as follows:

  <h4 class="no-num no-toc" id=unknown-properties>Unknown properties</h4>

  <p>Unknown properties are dropped.

  <h4 class="no-num no-toc" id=the-width-and-height-properties>The <code
   class=index id=width2 title="width!!viewport META">width</code> and <code
   class=index id=height2 title="height!!viewport META">height</code>
   properties</h4>

  <p>The <code class=index id=width3 title="width!!viewport
   META">width</code> and <code class=index id=height3
   title="height!!viewport META">height</code> viewport <code
   class=html>META</code> properties are translated into &lsquo;<a
   href="#width"><code class=property>width</code></a>&rsquo; and &lsquo;<a
   href="#height"><code class=property>height</code></a>&rsquo; shorthand
   properties, effectively setting the min and max properties to the same
   value.

  <ol>
   <li>Non-negative number values are translated to pixel lengths, clamped to
    the range: <code>[1px, 10000px]</code>

   <li>Negative number values are dropped

   <li><code class=index id=device-width1 title="device-width!!viewport
    META">device-width</code> and <code class=index id=device-height1
    title="device-height!!viewport META">device-height</code> are used as
    keywords

   <li>Other keywords and unknown values translate to 1px
  </ol>

  <p>For a viewport <code class=html>META</code> element that translates into
   an <code class=css>@viewport</code> rule with a non-&lsquo;<code
   class=css>auto</code>&rsquo; &lsquo;<a href="#zoom"><code class=property
   title="zoom!!property">zoom</code></a>&rsquo; declaration and no &lsquo;<a
   href="#width"><code class=property>width</code></a>&rsquo; declaration,
   add:

  <pre>width: auto;</pre>

  <p>to the <code class=css>@viewport</code> rule.

  <div class=example>
   <p>This <code class=html>META</code> element:</p>

   <pre><!--
	-->&lt;meta name="viewport" content="initial-scale=1.0"&gt;<!--
   --></pre>

   <p>translates into:</p>

   <pre><!--
	-->@viewport {
<!--	-->  zoom: 1.0;
<!--	-->  width: auto;
<!--	-->}<!--
   --></pre>
  </div>

  <h4 class="no-num no-toc" id=the-initial-scale-minimum-scale-and-maxi>The
   <code class=index id=initial-scale0>initial-scale</code>, <code
   class=index id=minimum-scale0>minimum-scale</code>, and <code class=index
   id=maximum-scale0>maximum-scale</code> properties</h4>

  <p>The properties are translated into &lsquo;<a href="#zoom"><code
   class=property title="zoom!!property">zoom</code></a>&rsquo;, &lsquo;<a
   href="#min-zoom"><code class=property>min-zoom</code></a>&rsquo;, and
   &lsquo;<a href="#max-zoom"><code class=property>max-zoom</code></a>&rsquo;
   respectively with the following translations of values.

  <ol>
   <li>Non-negative number values are translated to &lt;number&gt; values,
    clamped to the range <code>[0.1, 10]</code>

   <li>Negative number values are dropped

   <li><code class=index id=yes0>yes</code> is translated to 1

   <li><code class=index id=device-width2 title="device-width!!viewport
    META">device-width</code> and <code class=index id=device-height2
    title="device-height!!viewport META">device-height</code> are translated
    to 10

   <li><code class=index id=no0>no</code> and unknown values are translated
    to 0.1
  </ol>

  <p>For a viewport <code class=html>META</code> element that translates into
   an <code class=css> @viewport</code> rule with no &lsquo;<a
   href="#max-zoom"><code class=property>max-zoom</code></a>&rsquo;
   declaration and a non-&lsquo;<code class=css>auto</code>&rsquo; &lsquo;<a
   href="#min-zoom"><code class=property>min-zoom</code></a>&rsquo; value
   that is larger than the &lsquo;<a href="#max-zoom"><code
   class=property>max-zoom</code></a>&rsquo; value of the UA stylesheet, the
   &lsquo;<a href="#min-zoom"><code class=property>min-zoom</code></a>&rsquo;
   declaration value is clamped to the UA stylesheet &lsquo;<a
   href="#max-zoom"><code class=property>max-zoom</code></a>&rsquo; value.

  <h4 class="no-num no-toc" id=the-user-scalable-property>The <code
   class=index id=user-scalable0>user-scalable</code> property</h4>

  <p>The <code class=index id=user-scalable1>user-scalable</code> property is
   translated into &lsquo;<a href="#user-zoom"><code
   class=property>user-zoom</code></a>&rsquo; with the following value
   translations.

  <ol>
   <li><code class=index id=yes1>yes</code> and <code class=index
    id=no1>no</code> are translated into &lsquo;<a href="#zoom0"><code
    class=css title="zoom!!value">zoom</code></a>&rsquo; and &lsquo;<a
    href="#fixed"><code class=css>fixed</code></a>&rsquo; respectively.

   <li>Numbers &ge; 1, numbers &le; -1, <code class=index id=device-width3
    title="device-width!!viewport META">device-width</code> and <code
    class=index id=device-height3 title="device-height!!viewport
    META">device-height</code> are mapped to &lsquo;<a href="#zoom0"><code
    class=css title="zoom!!value">zoom</code></a>&rsquo;

   <li>Numbers in the range <code>&lt;-1, 1&gt;</code>, and unknown values,
    are mapped to &lsquo;<a href="#fixed"><code
    class=css>fixed</code></a>&rsquo;
  </ol>

  <div class=example>
   <p>This <code class=html>META</code> element:</p>

   <pre>&lt;meta name="viewport" content="width=480, initial-scale=2.0, user-scalable=1"&gt;</pre>

   <p>will translate into this <code class=css>@viewport</code> block:</p>

   <pre><!--
	-->@viewport {
<!--	-->  width: 480px;
<!--	-->  zoom: 2.0;
<!--	-->  user-zoom: zoom;
<!--	-->}<!--
   --></pre>
  </div>

  <h4 class="no-num no-toc" id=the-target-densitydpi-property>The <code
   class=index id=target-densitydpi0>target-densityDpi</code> property</h4>

  <p class=issue>At risk since &lsquo;<a href="#resolution"><code
   class=property>resolution</code></a>&rsquo; is at risk.

  <p class=note>This property differ from the others since it is from the
   WebKit implementation used in the Android browser and not supported in
   Safari

  <p>The <code class=index id=target-densitydpi1>target-densityDpi</code>
   property is translated into &lsquo;<a href="#resolution"><code
   class=property>resolution</code></a>&rsquo; with the following value
   translations.

  <ol>
   <li>Number values in the range <code>[70, 400]</code> are translated to
    &lsquo;<code class=css>dpi</code>&rsquo; values.

   <li><code class=index id=device-dpi>device-dpi</code> translates to
    &lsquo;<a href="#device"><code class=css>device</code></a>&rsquo;

   <li><code class=index id=low-dpi>low-dpi</code> translates to 120dpi

   <li><code class=index id=medium-dpi>medium-dpi</code> translates to 160dpi

   <li><code class=index id=high-dpi>high-dpi</code> translates to 240dpi

   <li>Other values are dropped
  </ol>

  <h2 id=handling-auto-zoom><span class=secno>11. </span>Handling &lsquo;<a
   href="#auto0"><code class=css title="auto!!zoom">auto</code></a>&rsquo;
   for &lsquo;<a href="#zoom"><code class=property
   title="zoom!!property">zoom</code></a>&rsquo;</h2>

  <p><em>This section is not normative.</em>

  <p>This section presents one way of picking an actual value for the
   &lsquo;<a href="#zoom"><code class=property
   title="zoom!!property">zoom</code></a>&rsquo; property when the used value
   is &lsquo;<a href="#auto0"><code class=css
   title="auto!!zoom">auto</code></a>&rsquo;.

  <p>Given an <a href="#initial-viewport">initial viewport</a> with size
   <code>(initial-width, initial-height)</code>, and a finite region within
   the <a href="http://www.w3.org/TR/CSS21/intro.html#canvas">canvas</a>
   where the formatting structure is rendered <code>(rendered-width,
   rendered-height)</code>. That region is at least as large as the <a
   href="#actual-viewport">actual viewport</a>.

  <p>Then, if the used value of &lsquo;<a href="#zoom"><code class=property
   title="zoom!!property">zoom</code></a>&rsquo; is &lsquo;<a
   href="#auto0"><code class=css title="auto!!zoom">auto</code></a>&rsquo;,
   let the actual zoom factor be:

  <pre>
<!---->zoom = MAX(initial-width / rendered-width, initial-height / rendered-height)<!--
 --></pre>

  <p>The actual zoom factor should also be further limited by the [min-zoom,
   max-zoom] range.

  <h2 class=no-num id=acknowledgments>Acknowledgments</h2>

  <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=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&#160;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=CSS3SYN>[CSS3SYN]

   <dd>L. David Baron. <a
    href="http://www.w3.org/TR/2003/WD-css3-syntax-20030813"><cite>CSS3
    module: Syntax.</cite></a> 13 August 2003. W3C Working Draft. (Work in
    progress.) URL: <a
    href="http://www.w3.org/TR/2003/WD-css3-syntax-20030813">http://www.w3.org/TR/2003/WD-css3-syntax-20030813</a>
    </dd>
   <!---->

   <dt id=CSS3VAL>[CSS3VAL]

   <dd>H&#229;kon Wium Lie; Chris Lilley. <a
    href="http://www.w3.org/TR/2006/WD-css3-values-20060919"><cite>CSS3
    Values and Units.</cite></a> 19 September 2006. W3C Working Draft. (Work
    in progress.) URL: <a
    href="http://www.w3.org/TR/2006/WD-css3-values-20060919">http://www.w3.org/TR/2006/WD-css3-values-20060919</a>
    </dd>
   <!---->

   <dt id=MEDIAQ>[MEDIAQ]

   <dd>H&#229;kon Wium Lie; et al. <a
    href="http://www.w3.org/TR/2010/CR-css3-mediaqueries-20100727/"><cite>Media
    Queries.</cite></a> 27 July 2010. W3C Candidate Recommendation. (Work in
    progress.) URL: <a
    href="http://www.w3.org/TR/2010/CR-css3-mediaqueries-20100727/">http://www.w3.org/TR/2010/CR-css3-mediaqueries-20100727/</a>
    </dd>
   <!---->
  </dl>
  <!--end-normative-->

  <h3 class=no-num id=other-references>Other references</h3>

  <dl class=bibliography>
   <dt id=Algorithms>[Algorithms]

   <dd>Thomas H. Cormen; et al. <cite>Introduction to Algorithms, Second
    Edition, MIT Press.</cite>
  </dl>

  <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&nbsp;to

     <th>Inh.

     <th>Percentages

     <th>Media

   <tbody>
    <tr>
     <th><a class=property href="#height">height</a>

     <td>&lt;viewport-length&gt;{1,2}

     <td>See individual properties

     <td>N/A

     <td>N/A

     <td>See individual properties

     <td>visual, continuous

    <tr>
     <th><a class=property href="#max-height">max-height</a>

     <td>&lt;viewport-length&gt;

     <td>auto

     <td>N/A

     <td>N/A

     <td>Refer to the height of the initial viewport

     <td>visual, continuous

    <tr>
     <th><a class=property href="#max-width">max-width</a>

     <td>&lt;viewport-length&gt;

     <td>auto

     <td>N/A

     <td>N/A

     <td>Refer to the width of the initial viewport

     <td>visual, continuous

    <tr>
     <th><a class=property href="#max-zoom">max-zoom</a>

     <td>auto | &lt;number&gt; | &lt;percentage&gt;

     <td>auto

     <td>N/A

     <td>N/A

     <td>The zoom factor itself

     <td>visual, continuous

    <tr>
     <th><a class=property href="#min-height">min-height</a>

     <td>&lt;viewport-length&gt;

     <td>auto

     <td>N/A

     <td>N/A

     <td>Refer to the height of the initial viewport

     <td>visual, continuous

    <tr>
     <th><a class=property href="#min-width">min-width</a>

     <td>&lt;viewport-length&gt;

     <td>auto

     <td>N/A

     <td>N/A

     <td>Refer to the width of the initial viewport

     <td>visual, continuous

    <tr>
     <th><a class=property href="#min-zoom">min-zoom</a>

     <td>auto | &lt;number&gt; | &lt;percentage&gt;

     <td>auto

     <td>N/A

     <td>N/A

     <td>The zoom factor itself

     <td>visual, continuous

    <tr>
     <th><a class=property href="#orientation">orientation</a>

     <td>auto | portrait | landscape

     <td>auto

     <td>N/A

     <td>N/A

     <td>N/A

     <td>visual, continuous

    <tr>
     <th><a class=property href="#resolution">resolution</a>

     <td>auto | device | &lt;resolution&gt;

     <td>auto

     <td>N/A

     <td>N/A

     <td>N/A

     <td>visual, continuous

    <tr>
     <th><a class=property href="#user-zoom">user-zoom</a>

     <td>zoom | fixed

     <td>zoom

     <td>N/A

     <td>N/A

     <td>N/A

     <td>visual, continuous

    <tr>
     <th><a class=property href="#width">width</a>

     <td>&lt;viewport-length&gt;{1,2}

     <td>See individual properties

     <td>N/A

     <td>N/A

     <td>See individual properties

     <td>visual, continuous

    <tr>
     <th><span class=property>zoom</span>

     <td>auto | &lt;number&gt; | &lt;percentage&gt;

     <td>auto

     <td>N/A

     <td>N/A

     <td>The zoom factor itself

     <td>visual, continuous
  </table>
  <!--end-properties-->

  <h2 class=no-num id=index>Index</h2>
  <!--begin-index-->

  <ul class=indexlist>
   <li>actual viewport, <a href="#actual-viewport" title="actual
    viewport"><strong>3.</strong></a>

   <li>auto
    <ul>
     <li>length, <a href="#auto" title="auto,
      length"><strong>5.1.</strong></a>

     <li>max-zoom, <a href="#auto2" title="auto,
      max-zoom"><strong>5.7.</strong></a>

     <li>min-zoom, <a href="#auto1" title="auto,
      min-zoom"><strong>5.6.</strong></a>

     <li>orientation, <a href="#auto3" title="auto,
      orientation"><strong>5.9.</strong></a>

     <li>resolution, <a href="#auto4" title="auto,
      resolution"><strong>5.10.</strong></a>

     <li>zoom, <a href="#auto0" title="auto, zoom"><strong>5.5.</strong></a>
    </ul>

   <li>device, <a href="#device" title=device><strong>5.10.</strong></a>

   <li>device-dpi, <a href="#device-dpi" title=device-dpi>#</a>

   <li>device-height, <a href="#device-height"
    title=device-height><strong>5.1.</strong></a>
    <ul>
     <li>viewport META, <a href="#device-height0" title="device-height,
      viewport META">10.3.</a>, <a href="#device-height1"
      title="device-height, viewport META">#</a>, <a href="#device-height2"
      title="device-height, viewport META">#</a>, <a href="#device-height3"
      title="device-height, viewport META">#</a>
    </ul>

   <li>device-width, <a href="#device-width"
    title=device-width><strong>5.1.</strong></a>
    <ul>
     <li>viewport META, <a href="#device-width0" title="device-width,
      viewport META">10.3.</a>, <a href="#device-width1" title="device-width,
      viewport META">#</a>, <a href="#device-width2" title="device-width,
      viewport META">#</a>, <a href="#device-width3" title="device-width,
      viewport META">#</a>
    </ul>

   <li>fixed, <a href="#fixed" title=fixed><strong>5.8.</strong></a>

   <li>height, <a href="#height" title=height><strong>5.4.</strong></a>
    <ul>
     <li>initial, <a href="#initial-height" title="height, initial">6.1.</a>

     <li>resolved, <a href="#height0" title="height, resolved">6.1.</a>

     <li>viewport META, <a href="#height1" title="height, viewport
      META">10.2.</a>, <a href="#height2" title="height, viewport
      META">#</a>, <a href="#height3" title="height, viewport META">#</a>
    </ul>

   <li>high-dpi, <a href="#high-dpi" title=high-dpi>#</a>

   <li>initial-scale, <a href="#initial-scale" title=initial-scale>10.2.</a>,
    <a href="#initial-scale0" title=initial-scale>#</a>

   <li>initial viewport, <a href="#initial-viewport" title="initial
    viewport"><strong>3.</strong></a>

   <li>landscape, <a href="#landscape"
    title=landscape><strong>5.9.</strong></a>

   <li>low-dpi, <a href="#low-dpi" title=low-dpi>#</a>

   <li>max-height, <a href="#max-height"
    title=max-height><strong>5.3.</strong></a>

   <li>maximum-scale, <a href="#maximum-scale" title=maximum-scale>10.2.</a>,
    <a href="#maximum-scale0" title=maximum-scale>#</a>

   <li>max-width, <a href="#max-width"
    title=max-width><strong>5.1.</strong></a>

   <li>max-zoom, <a href="#max-zoom" title=max-zoom><strong>5.7.</strong></a>
    

   <li>medium-dpi, <a href="#medium-dpi" title=medium-dpi>#</a>

   <li>min-height, <a href="#min-height"
    title=min-height><strong>5.3.</strong></a>

   <li>minimum-scale, <a href="#minimum-scale" title=minimum-scale>10.2.</a>,
    <a href="#minimum-scale0" title=minimum-scale>#</a>

   <li>min-width, <a href="#min-width"
    title=min-width><strong>5.1.</strong></a>

   <li>min-zoom, <a href="#min-zoom" title=min-zoom><strong>5.6.</strong></a>
    

   <li>no, <a href="#no" title=no>10.3.</a>, <a href="#no0" title=no>#</a>,
    <a href="#no1" title=no>#</a>

   <li>orientation, <a href="#orientation"
    title=orientation><strong>5.9.</strong></a>

   <li>portrait, <a href="#portrait" title=portrait><strong>5.9.</strong></a>
    

   <li>resolution, <a href="#resolution"
    title=resolution><strong>5.10.</strong></a>

   <li>&lt;resolution&gt;, <a href="#ltresolutiongt"
    title="&lt;resolution&gt;"><strong>5.10.</strong></a>

   <li>target-densityDpi, <a href="#target-densitydpi"
    title=target-densityDpi>10.2.</a>, <a href="#target-densitydpi0"
    title=target-densityDpi>#</a>, <a href="#target-densitydpi1"
    title=target-densityDpi>#</a>

   <li>user-scalable, <a href="#user-scalable" title=user-scalable>10.2.</a>,
    <a href="#user-scalable0" title=user-scalable>#</a>, <a
    href="#user-scalable1" title=user-scalable>#</a>

   <li>user-zoom, <a href="#user-zoom"
    title=user-zoom><strong>5.8.</strong></a>

   <li>&lt;viewport-length&gt;, <a href="#ltviewport-lengthgt"
    title="&lt;viewport-length&gt;"><strong>5.1.</strong></a>

   <li>width, <a href="#width" title=width><strong>5.2.</strong></a>
    <ul>
     <li>initial, <a href="#initial-width" title="width, initial">6.1.</a>

     <li>resolved, <a href="#width0" title="width, resolved">6.1.</a>

     <li>viewport META, <a href="#width1" title="width, viewport
      META">10.2.</a>, <a href="#width2" title="width, viewport META">#</a>,
      <a href="#width3" title="width, viewport META">#</a>
    </ul>

   <li>yes, <a href="#yes" title=yes>10.3.</a>, <a href="#yes0"
    title=yes>#</a>, <a href="#yes1" title=yes>#</a>

   <li>zoom
    <ul>
     <li>property, <a href="#zoom" title="zoom,
      property"><strong>5.5.</strong></a>

     <li>value, <a href="#zoom0" title="zoom,
      value"><strong>5.8.</strong></a>
    </ul>
  </ul>
  <!--end-index-->