.back-to-top {
    position: fixed;
    display: none;
    background: #5c2d78;
    color: #fff;
    width: 44px;
    height: 44px;
    text-align: center;
    line-height: 1;
    font-size: 38px;
    border-radius: 50%;
    right: 15px;
    bottom: 15px;
    transition: background 0.5s;
    z-index: 11;
}

.back-to-top:hover {
    color: #fff;
}