tab bar: fix incorrectly highlighted active tabs

overrides/partials/tabs-item.html

@@ -1,14 +1,4 @@
-{% if nav_item.is_homepage or nav_item.url == "index.html" %}
-  <li class="md-tabs__item">
-    {% set class = "md-tabs__link" %}
-    {% if not page.ancestors | length and nav | selectattr("url", page.url) %}
-      {% set class = "md-tabs__link md-tabs__link--active" %}
-    {% endif %}
-    <a href="{{ nav_item.url | url }}" class="{{ class }}">
-      {{ nav_item.title }}
-    </a>
-  </li>
-{% elif nav_item.children and nav_item.children | length > 0 %}
+{% if nav_item.children and nav_item.children | length > 0 %}
   {% set title = title | default(nav_item.title) %}
   {% if (nav_item.children | first).children %}
     {% set nav_item = nav_item.children | first %}
@@ -26,7 +16,11 @@
   {% endif %}
 {% else %}
   <li class="md-tabs__item">
-    <a href="{{ nav_item.url | url }}" class="md-tabs__link">
+    {% set class = "md-tabs__link" %}
+    {% if nav_item.active %}
+      {% set class = "md-tabs__link md-tabs__link--active" %}
+    {% endif %}
+	<a href="{{ nav_item.url | url }}" class="{{ class }}">
       {{ nav_item.title }}
     </a>
   </li>