Fix custom tag layout which regressed in #5309

Signed-off-by: Aaron Raimist <aaron@raim.ist>

res/css/structures/_LeftPanel.scss

@@ -32,6 +32,7 @@ $groupFilterPanelWidth: 56px; // only applies in this file, used for calculation
 
         // Create another flexbox so the GroupFilterPanel fills the container
         display: flex;
+        flex-direction: column;
 
         // GroupFilterPanel handles its own CSS
     }