body { 
     background-color: #efefef;
     background-image:url(https://img2018.cnblogs.com/common/1925396/202001/1925396-20200120112622949-195627410.jpg); 
     background-repeat: no-repeat; 
     background-attachment: fixed; 
     background-position: center 0; 
     background-size: cover; 
    padding-top:0px;
  }