[Glitch] Change composer highlight border size to be more noticeable

Port aa4c9730f6 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/styles/components/columns.scss

@@ -1243,7 +1243,7 @@ $ui-header-height: 55px;
 
   &.active {
     transition: none;
-    box-shadow: 0 0 0 2px rgba(lighten($highlight-text-color, 8%), 0.7);
+    box-shadow: 0 0 0 6px rgba(lighten($highlight-text-color, 8%), 0.7);
   }
 }