Add respond.js to main docs pages, but only for IE8 and down

docs/css.html

@@ -15,6 +15,7 @@
     <!-- Le HTML5 shim, for IE6-8 support of HTML5 elements -->
     <!--[if lt IE 9]>
       <script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
+      <script src="assets/js/respond/respond.js"></script>
     <![endif]-->
 
     <!-- Le fav and touch icons -->
@@ -2407,6 +2408,5 @@ For example, &lt;code&gt;&amp;lt;section&amp;gt;&lt;/code&gt; should be wrapped
     <script src="assets/js/application.js"></script>
 
 
-
   </body>
 </html>