body {
    text-align: center;
    margin: 0;
  }
  #bg {
    width: 100%;
    height: auto;
  }
  #title {
    font-size: 80px;
    color: white;
  }
  #app {
    top: 300px;
    position: absolute;
    width:100%;
    text-align:center;
  }
  #market {
    margin-top: 80px;
    width:100%;
    text-align:center;
  }
  .show{
      display: block;
  }
  #wechat {
      font-size: 36px;
  }