修改背景图样式

src/pages/activity/index.vue

@@ -1,5 +1,5 @@
 <template>
-  <view class='app-container'>
+  <view class='app-container' :style="{'height': pic ? '' : '100%'}">
     <img :src="pic" />
     <button class="submit" type="submit" circle @click="getSubmit">立即兑换</button>