/* 返回顶部按钮样式 - 仅在移动端显示 */
#backToTop {
    position: fixed;
    bottom: 80px;
    right: 20px;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, #6b46c1 0%, #9f7aea 100%);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 999;
    box-shadow: 0 4px 12px rgba(107, 70, 193, 0.4);
    display: flex;
    align-items: center;
    justify-content: center;
}

#backToTop.visible {
    opacity: 1;
    visibility: visible;
}

#backToTop:hover {
    background: linear-gradient(135deg, #553c9a 0%, #805ad5 100%);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(107, 70, 193, 0.5);
}

#backToTop:active {
    transform: translateY(0);
}

/* 桌面端隐藏返回顶部按钮 */
@media (min-width: 768px) {
    #backToTop {
        display: none !important;
    }
}

/* 移动端优化 */
@media (max-width: 767px) {
    #backToTop {
        display: flex;
    }
}