body{
   background-color:#efefef;
   background-image:url(https://img2020.cnblogs.com/blog/2261298/202101/2261298-20210114203648756-1282159834.png);
   background-repeat:no-repeat;
   background-attachment:fixed;
   background-position:center 0;
   background-size: cover;
   padding-top:0px;
   opacity:0.6
}