/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: var(--accent);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    cursor: pointer;
    box-shadow: 0 2px 15px rgba(0, 0, 0, 0.2);
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background-color: var(--primary);
    transform: translateY(-3px);
}

/* 页脚 */
footer {
    background: var(--dark);
    color: white;
    padding: 4rem 5% 0;
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
}

.footer-column h3 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    position: relative;
    padding-bottom: 0.8rem;
}

.footer-column h3:after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 3px;
    background: var(--accent);
}

.footer-column p {
    color: #aaa;
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.8rem;
}

.footer-links a {
    color: #aaa;
    text-decoration: none;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.8rem;
}

.footer-links a:hover {
    color: var(--accent);
    transform: translateX(5px);
}

.footer-links i {
    color: var(--accent);
}

.contact-info p {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    margin-bottom: 1rem;
}

.contact-info i {
    color: var(--accent);
    min-width: 20px;
}

.social-icons {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}

.social-icons a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: #333;
    color: white;
    border-radius: 50%;
    transition: var(--transition);
}

.social-icons a:hover {
    background: var(--accent);
    transform: translateY(-5px);
}

.copyright {
    text-align: center;
    padding: 1.5rem;
    border-top: 1px solid #333;
    margin-top: 3rem;
    color: #aaa;
    font-size: 0.9rem;
}

.copyright a{
    color: #aaa;
}

/* 动画效果 */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes float {
    0% { transform: translateY(0px); }
    50% { transform: translateY(-15px); }
    100% { transform: translateY(0px); }
}

/* 响应式设计 */
@media (max-width: 992px) {
    .about-intro {
        flex-direction: column;
    }

    .intro-image {
        order: -1;
        margin-bottom: 2rem;
        max-width: 600px;
    }

    .mission-vision {
        flex-direction: column;
    }

    .timeline:before {
        left: 30px;
    }

    .timeline-item {
        width: 100%;
        padding-left: 70px;
        padding-right: 0;
        text-align: left !important;
    }

    .timeline-item:nth-child(odd):after,
    .timeline-item:nth-child(even):after {
        left: 20px;
        right: auto;
    }

    .culture-container {
        flex-direction: column;
    }
    /* 移动端返回顶部按钮 */
    .back-to-top {
        width: 45px;
        height: 45px;
        bottom: 20px;
        right: 20px;
    }
}

@media (max-width: 768px) {
    .navbar {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }

    .nav-links {
        gap: 1rem;
        flex-wrap: wrap;
        justify-content: center;
    }

    .about-hero h1 {
        font-size: 2.5rem;
    }

    .hero-stats {
        gap: 1.5rem;
    }

    .stat-box {
        padding: 1rem 1.5rem;
        min-width: 160px;
    }

    .stat-box .number {
        font-size: 2rem;
    }

    .values-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .about-hero h1 {
        font-size: 2rem;
    }

    .hero-stats {
        flex-direction: column;
        align-items: center;
    }

    .stat-box {
        width: 100%;
        max-width: 250px;
    }

    .section-title h2 {
        font-size: 2rem;
    }
}