[Doc] optimzie demo display (#626)

docs/src/WapApp.vue

@@ -1,7 +1,37 @@
 <template>
-  <router-view />
+  <div>
+    <van-nav-bar
+      v-show="title"
+      fixed
+      class="van-doc-nav-bar"
+      :title="title"
+      left-arrow
+      :left-text="$t('back')"
+      @click-left="onBack"
+    />
+    <router-view />
+  </div>
 </template>
 
+<script>
+import { camelize } from 'packages/utils';
+
+export default {
+  computed: {
+    title() {
+      const name = this.$route.name;
+      return name ? camelize(name.split('/').pop()) : '';
+    }
+  },
+
+  methods: {
+    onBack() {
+      history.back();
+    }
+  }
+};
+</script>
+
 <style lang="postcss">
 body {
   color: #333;
@@ -10,4 +40,14 @@ body {
   font-family: Arial, Helvetica, "STHeiti STXihei", "Microsoft YaHei", Tohoma, sans-serif;
   -webkit-font-smoothing: antialiased;
 }
+
+.van-doc-nav-bar {
+  .van-nav-bar__title {
+    text-transform: capitalize;
+  }
+}
+
+.van-doc-demo-section {
+  padding-top: 46px;
+}
 </style>