body{
    background-image: url("https://images.cnblogs.com/cnblogs_com/lora404/1667107/o_200311075515leaves-pattern.png");
    background-position: initial;
    background-size: cover;
    background-repeat: no-repeat;
    background-attachment: fixed;
    background-origin: initial;
    background-clip: initial;
    height:100%;
    width:100%;
    }