Initial support for Navigation module Beta

Closes #3441940

dist/css/base/gin.css

@@ -1486,7 +1486,7 @@ table td .group-label {
 }
 
 .sortable-heading > a::before {
-  bottom: -1px;
+  bottom: -2px;
 }
 
 .sortable-heading > a::after {