.back_top {
    //display: flex;
    flex-direction: column;
    align-items: center;
    position: fixed;
    right: 0;
    bottom: 50px;
    cursor: pointer;
    display: none;
  }
  
  .back_top img {
    //width: 21px;
    height: 29px;
    margin-bottom: 3px;
    padding-left: 35%;
  }
  
  .back_top span {
    width: 63px;
    height: 54px;
    background: #7b857e;
    font-size: 20px;
    font-family: Microsoft YaHei;
    font-weight: 400;
    color: #ffffff;
    line-height: 23px;
    display: flex;
    justify-content: center;
    align-items: center;
  }