#toTop {
    background: url(https://images.cnblogs.com/cnblogs_com/BlogOfchc1234567890/1343435/o_top_.jpg) no-repeat 0px top;
    width: 75px;
    height: 23px;
    overflow: hidden;
    position: fixed;
    right: 170px;
    bottom: 20px;
    cursor: pointer;
  opacity : 0.85
}

#clockdiv {
    /* left, center, right */
    text-align: center;
}

body { 
     background-color: #efefef;
     background-image:url(https://images.cnblogs.com/cnblogs_com/BlogOfchc1234567890/1343435/o_timg.jpg); 
     background-repeat: no-repeat; 
     background-attachment: fixed; 
     background-position: center 0; 
     background-size: cover; 
    padding-top:0px;
  opacity: 0.75
  }