Give sticky_side z-index 1, important for narrow mode.

Without this, the grid-view album cards were displaying above
the sticky toolbox because of their position:relative, which
I can't get rid of at the moment.

frontends/etiquette_flask/static/css/common.css

@@ -133,6 +133,7 @@ pre
     display: grid;
     grid-auto-rows: min-content;
 
+    z-index: 1;
     position: fixed;
     bottom: 8px;
     top: 34px;