update grid col mixin to use latest css from grid cols

less/mixins.less

@@ -443,9 +443,6 @@
 // Generate the columns
 .make-column(@columns) {
   position: relative;
-  // Float and set width: 100%; for easy stacking on mobile devices
-  float: left;
-  width: 100%;
   // Prevent columns from collapsing when empty
   min-height: 1px;
   // Inner gutter via padding
@@ -454,6 +451,7 @@
 
   // Calculate width based on number of columns available
   @media (min-width: @grid-float-breakpoint) {
+    float: left;
     width: percentage((@columns / @grid-columns));
   }
 }