ios滚动 fix布局顶栏消逝

  #box{
    position: relative;
    height: 100vh;
    .tit{
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      .wh(auto,.8rem);
      background: #f4f4f8;
      z-index: 1;
    }
    .list{
      position: absolute;
      top: .8rem;
      left: 0;
      right: 0;
      bottom: 0;
      overflow-y: auto;
      -webkit-overflow-scrolling:touch;   //这里很重要设置元素overfllow-y:auto; 导致ios滚动不流畅，必须加上
      padding: .3rem;
    }
  }