Vertically center caret

services/web/public/stylesheets/components/dropdowns.less

@@ -13,6 +13,7 @@
   border-top:   @caret-width-base solid;
   border-right: @caret-width-base solid transparent;
   border-left:  @caret-width-base solid transparent;
+  margin-top:   -@caret-width-base/2;
 }
 
 // The dropdown wrapper (div)