docs: update site ui

Signed-off-by: Bobby DeSimone <bobbydesimone@gmail.com>

docs/.vuepress/theme/components/DropdownLink.vue

@@ -0,0 +1,179 @@
+<template>
+  <div
+    class="dropdown-wrapper"
+    :class="{ open }"
+  >
+    <a
+      class="dropdown-title"
+      @click="toggle"
+    >
+      <span class="title">{{ item.text }}</span>
+      <span
+        class="arrow"
+        :class="open ? 'down' : 'right'"
+      ></span>
+    </a>
+
+    <DropdownTransition>
+      <ul
+        class="nav-dropdown"
+        v-show="open"
+      >
+        <li
+          class="dropdown-item"
+          :key="subItem.link || index"
+          v-for="(subItem, index) in item.items"
+        >
+          <h4 v-if="subItem.type === 'links'">{{ subItem.text }}</h4>
+
+          <ul
+            class="dropdown-subitem-wrapper"
+            v-if="subItem.type === 'links'"
+          >
+            <li
+              class="dropdown-subitem"
+              :key="childSubItem.link"
+              v-for="childSubItem in subItem.items"
+            >
+              <NavLink :item="childSubItem"/>
+            </li>
+          </ul>
+
+          <NavLink
+            v-else
+            :item="subItem"
+          />
+        </li>
+      </ul>
+    </DropdownTransition>
+  </div>
+</template>
+
+<script>
+import NavLink from '@theme/components/NavLink.vue'
+import DropdownTransition from '@theme/components/DropdownTransition.vue'
+
+export default {
+  components: { NavLink, DropdownTransition },
+
+  data () {
+    return {
+      open: false
+    }
+  },
+
+  props: {
+    item: {
+      required: true
+    }
+  },
+
+  methods: {
+    toggle () {
+      this.open = !this.open
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+.dropdown-wrapper
+  cursor pointer
+  .dropdown-title
+    display block
+    &:hover
+      border-color transparent
+    .arrow
+      vertical-align middle
+      margin-top -1px
+      margin-left 0.4rem
+  .nav-dropdown
+    .dropdown-item
+      color inherit
+      line-height 1.7rem
+      h4
+        margin 0.45rem 0 0
+        border-top 1px solid #eee
+        padding 0.45rem 1.5rem 0 1.25rem
+      .dropdown-subitem-wrapper
+        padding 0
+        list-style none
+        .dropdown-subitem
+          font-size 0.9em
+      a
+        display block
+        line-height 1.7rem
+        position relative
+        border-bottom none
+        font-weight 400
+        margin-bottom 0
+        padding 0 1.5rem 0 1.25rem
+        &:hover
+          color $accentColor
+        &.router-link-active
+          color $accentColor
+          &::after
+            content ""
+            width 0
+            height 0
+            border-left 5px solid $accentColor
+            border-top 3px solid transparent
+            border-bottom 3px solid transparent
+            position absolute
+            top calc(50% - 2px)
+            left 9px
+      &:first-child h4
+        margin-top 0
+        padding-top 0
+        border-top 0
+
+@media (max-width: $MQMobile)
+  .dropdown-wrapper
+    &.open .dropdown-title
+      margin-bottom 0.5rem
+    .nav-dropdown
+      transition height .1s ease-out
+      overflow hidden
+      .dropdown-item
+        h4
+          border-top 0
+          margin-top 0
+          padding-top 0
+        h4, & > a
+          font-size 15px
+          line-height 2rem
+        .dropdown-subitem
+          font-size 14px
+          padding-left 1rem
+
+@media (min-width: $MQMobile)
+  .dropdown-wrapper
+    height 1.8rem
+    &:hover .nav-dropdown
+      // override the inline style.
+      display block !important
+    .dropdown-title .arrow
+      // make the arrow always down at desktop
+      border-left 4px solid transparent
+      border-right 4px solid transparent
+      border-top 6px solid $arrowBgColor
+      border-bottom 0
+    .nav-dropdown
+      display none
+      // Avoid height shaked by clicking
+      height auto !important
+      box-sizing border-box;
+      max-height calc(100vh - 2.7rem)
+      overflow-y auto
+      position absolute
+      top 100%
+      right 0
+      background-color #fff
+      padding 0.6rem 0
+      border 1px solid #ddd
+      border-bottom-color #ccc
+      text-align left
+      border-radius 0.25rem
+      white-space nowrap
+      margin 0
+</style>