fix(grid): stackable grid had wrong with inside popup

A stackable grid inside a popup did not have enough specificity to adjust the width on mobile views

Author: lubber-de

src/definitions/collections/grid.less

@@ -1659,7 +1659,7 @@ each(@colors, {
   --------------------*/
 
   @media only screen and (max-width: @largestMobileScreen) {
-    .ui.stackable.grid {
+    .ui.ui.ui.ui.stackable.grid {
       width: auto;
       margin-left: 0 !important;
       margin-right: 0 !important;