body {
 background-size: 100%;
    background-repeat: no-repeat;  
   background: rgba(12, 100, 129, 0)  fixed;
 background-image:url('https://images.cnblogs.com/cnblogs_com/huangzedong/1601886/o_5aeb0fdd51b7e.jpg');
background-attachment: fixed;
 
   
    font-family: "Helvetica Neue",Helvetica,Verdana,Arial,sans-serif;
    font-size: 12px;
    min-height: 101%;

  filter: alpha(opacity=50); opacity:0.8;
}