html{
    scroll-behavior: smooth;
}
#back2Top {
    width: 40px;
    line-height: 40px;
    overflow: hidden;
    z-index: 999;
    display: none;
    cursor: pointer;
    position: fixed;
    bottom: 10px;
    right: 20px;
    text-align: center;
    font-size: 15px;
    border-radius: 4px;
    text-decoration: none;
    background: #333c56;
    color: #fff;
}