proper var

less/navbar.less

@@ -92,7 +92,7 @@
   .navbar-collapse {
     max-height: @navbar-collapse-max-height;
 
-    @media (max-width: @screen-phone) and (orientation: landscape) {
+    @media (max-width: @screen-xs-min) and (orientation: landscape) {
       max-height: 200px;
     }
   }