<wx-open-launch-weapp
      id="xxx"
      username="gh_xxxxxxxxx"
      path="pages/index/index.html"
      @ready="btnReady"
      @launch="btnLaunch"
      @error="btnError"
    >
      <script type="text/wxtag-template">
        <style>
          .btn {
            width: 300px;
            height: 100px;
            min-height: 100px;
            line-height: 100px;
            text-align: center;
            color: #444;
            font-size: 14px;
            display: inline-block;
            background: #fff100;
            border-radius: 100px;
            border: 0;
            padding: 0 10px;
          }
        </style>
        <button class="btn" >打开小程序</button>
      </script>
    </wx-open-launch-weapp>