/* 回到顶部按钮样式 */
#scroll-top-btn {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: #8B0000;
    color: #fff;
    border-radius: 50%;
    text-align: center;
    line-height: 50px;
    font-size: 24px;
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transition: 0.3s;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

#scroll-top-btn.show {
    opacity: 1;
    visibility: visible;
}

#scroll-top-btn:hover {
    background-color: #003d82;
    transform: translateY(-5px);
}