.haha-backToTop{
    height:2.81rem;
    position:fixed;
    width:2.81rem;
    background:url('https://cdn.xueyuan.xiaobao100.com/shield/image/topbtn.png') no-repeat center;
    background-size:100%;
    right:1rem;
    bottom: 4.69rem;
    z-index: 1010;
}