Fix navbar-toggle after commit bbee78b3

The following commit introduced an issue with the navbar toggle placement:
https://github.com/twitter/bootstrap/commit/bbee78b30b40ff0b1473a06ea7ecf5a42d51b614

less/navbar.less

@@ -96,7 +96,7 @@
 // Collapsible navbar toggle
 .navbar-toggle {
   position: absolute;
-  top: 18px;
+  top: 10px;
   right: 10px;
   padding: 8px 12px;
   background-color: transparent;