body{
    background-image: url(https://img2020.cnblogs.com/blog/1906328/202011/1906328-20201104140108219-1053129839.jpg);
    background-position: initial;
    background-size: cover;
    background-repeat: no-repeat;
    background-attachment: fixed;
    background-origin: initial;
    background-clip: initial;
    height:100%;
    width:100%;
    }