fix broken dropdowns in ie7 per #2333

docs/assets/css/bootstrap.css

@@ -2730,6 +2730,8 @@ input[type="submit"].btn.btn-small {
   *border-left-color: #ffffff;
 }
 .navbar {
+  *position: relative;
+  *z-index: 2;
   overflow: visible;
   margin-bottom: 18px;
 }

less/navbar.less

@@ -6,6 +6,10 @@
 // -------------
 
 .navbar {
+  // Fix for IE7's bad z-indexing so dropdowns don't appear below content that follows the navbar
+  *position: relative;
+  *z-index: 2;
+
   overflow: visible;
   margin-bottom: @baseLineHeight;
 }