Put a watermark on my non background slides.

@@ -21,6 +21,7 @@
 	</div>
 </div>
 <div id="section2" class="section">
+	<%= image_tag "dogs2.svg", class: "watermark" %>
 	<div class="content">
 		<h2>This is mostly about programming.</h2>
 		<p>
@@ -51,6 +52,7 @@
 	</div>
 </div>
 <div id="section4" class="section">
+	<%= image_tag "dogs2.svg", class: "watermark" %>
 	<div class="content">
 		<h1>Other</h1>
 		<p>