Bugfix: only direct descendants of .dragged-over get overlay styling …

…applied

  - dragging items over the *any* idea column was causing *all* idea column's 'overlay' elements to get styling applied multiple times, causing a difference in the apparent opacity of the overlay

web/static/js/components/css_modules/idea_drop_target.css

@@ -2,7 +2,7 @@
 :global(.dragged-over) {
   position: relative;
 
-  :global(.overlay) {
+  :global(> .overlay) {
     position: absolute;
     top: 0;
     left: 0;