#backToTop {
    position: fixed;
    right: 20px;
    bottom: 70px;
    width: 44px;
    height: 44px;
    border-radius: 999px;
    background: #111827;
    color: #ffffff;
    border: none;
    font-size: 18px;
    cursor: pointer;
    box-shadow: 0 10px 25px rgba(0,0,0,.4);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all .3s ease;
    z-index: 9999;
}

#backToTop.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

#backToTop:hover {
    background: #1f2937;
}