.scroll-top-btn {
    position: fixed;
    bottom: 30px;
    right: 20px;
    background: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: 50%;
    width: 45px;
    height: 45px;
    cursor: pointer;
    box-shadow: var(--shadow);
    transition: background 0.3s, box-shadow 0.3s;
}

.scroll-top-btn:hover {
    background: var(--button-hover-bg);
    box-shadow: 0 15px 25px rgba(0, 0, 0, 0.15);
}