body:before {
    background: url(https://images.cnblogs.com/cnblogs_com/wh2020/1832338/o_20082100141511.jpg) center/cover no-repeat;
    content: '';
    background-repeat: no-repeat;
    background-position: center;
    opacity: 0.8;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    -webkit-filter: grayscale(40%);
    -moz-filter: grayscale(40%);
    -ms-filter: grayscale(40%);
    -o-filter: grayscale(40%);
    filter: grayscale(40%);
    filter: gray;
}

.cd-top {
    position: fixed;
    right: 25px;
    top: -900px;
    z-index: 99;
    width: 70px;
    height: 900px;
    background: url(https://cdn.jsdelivr.net/gh/moezx/cdn@3.1.9/img/Sakura/images/scroll.png) no-repeat center;
    background-size: contain;
    -webkit-transition: all .5s ease-in-out;
    transition: all .5s ease-in-out;
    cursor: url(https://cdn.jsdelivr.net/gh/moezx/cdn@3.1.9/img/Sakura/cursor/No_Disponible.cur), auto;
    opacity: 1
}
.cd-top.cd-is-visible {
    opacity: 1;
    top: -326px
}
.cd-top.cd-fade-out {
    opacity: 1
}
.cd-top:hover {
    opacity: 1
}
.cd-top span {
    display: none;
    color: #000;
    position: absolute;
    bottom: 0;
    height: 20px;
    width: 50px;
    text-align: center
}
@media screen and (max-width:860px) {
    .cd-top {
        display: none;
        height: 60px;
        width: 50px
    }
    .cd-top span {
        height: 10px;
        width: 50px
    }
}