Make our portico bottom copyright and navigation stick to the bottom of the page

We use the technique described here:
http://ryanfait.com/resources/footer-stick-to-bottom-of-page/

(imported from commit 108f3c9cc4ce9dbf483ff76d6f9a6a014077da56)

templates/zephyr/portico.html

@@ -44,7 +44,10 @@ hence the name.
   </div>
   {% endblock %}
 
-  <div class="navbar">
+  <div class="push"></div>
+</div>
+
+<div class="navbar footer">
   <div class="content">
     <ul class="nav pull-right">
       <li><span class="navbar-text">Humbug © 2013</span></li>
@@ -57,5 +60,4 @@ hence the name.
     </ul>
   </div>
 </div>
-</div>
 {% endblock %}

zephyr/static/styles/portico.css

@@ -1,5 +1,12 @@
 .container-fluid {
     padding: 0px;
+    min-height: 100%;
+
+    /* Hack for IE */
+    height: auto !important;
+    height: 100%;
+
+    margin: 0 auto -41px;
 }
 
 /* This is a hack so that our main content
@@ -21,9 +28,18 @@
     -moz-border-radius: 0px;
 }
 
+.footer, .push {
+    height: 41px;
+}
+
+html {
+    height: 100%;
+}
+
 body {
     font-family: 'Humbug', Helvetica, Arial, sans-serif;
     line-height: 150%;
+    height: 100%;
 }
 
 li {