body{
    width:80%;
    background: url(https://images.cnblogs.com/cnblogs_com/dreamcenter/1606455/o_191204080826bk.jpg) fixed;
    background-size:cover;
    background-repeat: no-repeat;
    
    font-family: "Helvetica Neue",Helvetica,Verdana,Arial,sans-serif;

    margin: 0 auto;
}