.scroll-to-top-btn {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--primary-color);
    color: #fff;
    font-size: 24px;
    z-index: 999;
    border: 2px solid #fff;
    align-items: center;
    justify-content: center;
    display: none;
}

.scroll-to-top-btn.visible {
    display: flex;
}

.scroll-to-top-btn:hover {
    background: var(--secondary-color);
    color: #fff;
    transform: translateY(-3px);
}