Updated menu item style to use active state

Instead of looking for the `.active` class, we'll use `data-state="active"` as our check which aligns with the `MenuItem` scope.

Milestone: minor

Author: bkuhlmann

app/assets/css/layout.css

@@ -160,7 +160,7 @@
     text-decoration: none;
     transition: border-bottom-color 0.3s ease-in-out;
 
-    &:hover, &:active, &.active {
+    &:hover, &:active, &[data-state="active"] {
       border-bottom-color: var(--site-orange);
     }
   }