html {
    scroll-behavior: smooth;
  }
#page-top{
    display: none;
    right: 10px;
    bottom: 10px;
    opacity: 0.8;
    position: fixed;
    padding: 5px;
    z-index: 10000;
    color: #fff;
    font-weight: bold;
    text-align: center;
    text-decoration: none;
    width: 40px;
    cursor: pointer;
    font-size: 14px;
}
#page-top span{
    color: #fff;
}
@media screen and (min-width: 641px) {
    #page-top{
        width: 90px;
        line-height: 80px;
        background: #929292;
        right: 0;
        bottom: 30px;
    }
    #page-top img {
        display: none;
    }
}
@media screen and (max-width: 640px){
    #page-top {
        height: 40px;
        line-height: 40px;
        align-items: center;
        background: #292929;
    }
    #page-top img {
        display: inline-block;
        width: 20px;
    }
    #page-top span {
        display: none;
    }
}