set z-index for tooltips

templates/client/default/assets/css/layers-ui.css

@@ -17275,6 +17275,7 @@ Rail
   color: #b3b5b9;
   vertical-align: text-bottom;
   margin-left: 8px;
+  z-index: 1;
 }
 
 #layers .lu-form-check label {