tweak: sidebar nav items

lib/default-theme/DropdownLink.vue

 <template>
   <div class="dropdown-wrapper" :class="{ open }">
-    <div class="dropdown-title" @click="toggle">
+    <a class="dropdown-title" @click="toggle">
       <span class="title">{{ item.text }}</span>
       <span class="arrow"></span>
-    </div>
+    </a>
     <ul class="nav-dropdown">
       <li
         class="dropdown-item"
@@ -53,6 +53,7 @@ export default {
 
 .dropdown-wrapper
   .dropdown-title
+    display block
     .arrow
       display inline-block
       vertical-align middle

lib/default-theme/Sidebar.vue

@@ -81,10 +81,11 @@ function resolveOpenGroupIndex (route, items) {
     display none
     border-bottom 1px solid $borderColor
     padding 0.5rem 0 0.75rem 0
+    a
+      font-weight 600
     .nav-item, .github-link
       display block
       line-height 1.25rem
-      font-weight 600
       font-size 1.1em
       padding 0.5rem 0 0.5rem 1.5rem
   .sidebar-links