#backToTopBtn {
    position: fixed;
    bottom: 20px;
    right: 30px;
    z-index: 99;
    font-size: 16px;
    border: none;
    outline: none;
    background-color: #555;
    color: white;
    cursor: pointer;
    padding: 15px;
    border-radius: 50%;
    opacity: 0.7;
    transition: opacity 0.3s;
}

#backToTopBtn:hover {
    opacity: 1;
}