#scrollToTopBtn {
    position: fixed;
    bottom: 50px;
    right: 50px;
    width: 50px;
    height: 50px;
    background: url('../totop.png') no-repeat center center;
    background-size: contain;
    border: none;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

#scrollToTopBtn.show {
    opacity: 1;
    visibility: visible;
}