#scroll-to-top {
    transition: opacity 0.3s ease-in-out, transform 0.3s ease-in-out;
    opacity: 0;
    transform: translateY(20px);
    pointer-events: none; /* prevent clicks when hidden */
    z-index: 999;
}

#scroll-to-top.visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}