#back-to-top {
    position: fixed;
    bottom: 20px;
    right: 20px;
    display: none;
    background-color: #007bff;
    color: #ffffff;
    width: 60px;
    height: 60px;
    text-align: center;
    line-height: 60px;
    border-radius: 50%;
    cursor: pointer;
    z-index: 99;
}

#back-to-top:hover {
    background-color: #FFC107;
}