Merge pull request #12330 from overleaf/jel-grid-3-and-4-col

[web] Add 3 and 4 column options to `Layout | Grid` on the CMS

GitOrigin-RevId: 6003907344bb84c16678ff4e4424b9348a4cb0df

services/web/frontend/stylesheets/app/cms-page.less

@@ -379,3 +379,11 @@
     }
   }
 }
+
+.reverse-col-order-mobile {
+  @media (max-width: @screen-sm-min) {
+    display: flex;
+    flex-flow: column;
+    flex-direction: column-reverse;
+  }
+}