Fixes the small gap above the nav menu dropdown boxes and the hoverable

menu items that was causing the dropdowns to go away when the user
moved their mouse down towards them.

docs/css/main.css

@@ -73,8 +73,13 @@ a:hover code {
  * using solution at http://stackoverflow.com/questions/8878033/how-
  * to-make-twitter-bootstrap-menu-dropdown-on-hover-rather-than-click
  **/
+.dropdown-menu {
+  /* Remove the default 2px top margin which causes a small
+    gap between the hover trigger area and the popup menu */
+  margin-top: 0;
+}
 ul.nav li.dropdown:hover ul.dropdown-menu{
-    display: block;
+  display: block;
 }
 a.menu:after, .dropdown-toggle:after {
   content: none;