remove tabindex

src/components/Header.vue

@@ -23,8 +23,8 @@
     </span>
     <span v-if="$parent.collapsed && $parent.has_content" class="definition_snippet">
       - {{$parent.snippet}}
-    </span>                <span v-if="$parent.collapsable" aria-hidden="true" tabindex=-1>
-          <v-btn tabindex=-1
+    </span>                <span v-if="$parent.collapsable">
+          <v-btn
            text
            small
            plain