/* AI创新创业协会网站样式表 */

:root {
    --primary: #4a90e2;
    --primary-dark: #2c5282;
    --primary-light: #63b3ed;
    --accent: #48bb78;
    --accent-dark: #38a169;
    --dark: #1a202c;
    --dark-secondary: #2d3748;
    --light: #f7fafc;
    --gray: #718096;
    --gray-light: #e2e8f0;
    --bg: #f0f7ff;
    --card-bg: #ffffff;
    --shadow: 0 4px 20px rgba(0,0,0,0.08);
    --shadow-hover: 0 10px 30px rgba(0,0,0,0.12);
    --radius: 16px;
    --radius-sm: 10px;
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.7;
    color: var(--dark);
    background: var(--bg);
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--primary-dark);
}

img {
    max-width: 100%;
    height: auto;
}

/* ========== 导航栏 ========== */
nav {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    box-shadow: 0 1px 10px rgba(0,0,0,0.06);
    z-index: 1000;
    transition: var(--transition);
}

nav.scrolled {
    box-shadow: 0 2px 20px rgba(0,0,0,0.1);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0.8rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--primary);
}

.logo img {
    width: 38px;
    height: 38px;
    border-radius: 50%;
    object-fit: cover;
    border: 2px solid var(--primary);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 0.5rem;
}

.nav-menu a {
    color: var(--dark-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    transition: var(--transition);
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary);
    background: rgba(74, 144, 226, 0.08);
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--primary);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 8px;
    transition: var(--transition);
}

.menu-toggle:hover {
    background: rgba(74, 144, 226, 0.08);
}

/* ========== Hero区 ========== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: linear-gradient(135deg, #1a365d 0%, #2c5282 40%, #4a90e2 100%);
    color: white;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
        radial-gradient(circle at 20% 50%, rgba(99, 179, 237, 0.3) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(72, 187, 120, 0.2) 0%, transparent 50%);
}

.hero::after {
    content: '';
    position: absolute;
    inset: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 60 60"><circle cx="30" cy="30" r="1" fill="white" opacity="0.05"/></svg>') repeat;
    background-size: 60px 60px;
}

.hero-content {
    position: relative;
    z-index: 1;
    padding: 2rem;
    max-width: 700px;
}

.hero-badge {
    display: inline-block;
    background: rgba(255,255,255,0.15);
    backdrop-filter: blur(8px);
    padding: 0.5rem 1.5rem;
    border-radius: 50px;
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
    border: 1px solid rgba(255,255,255,0.2);
    animation: fadeInUp 0.8s ease;
}

.hero h1 {
    font-size: 3.2rem;
    font-weight: 800;
    margin-bottom: 0.8rem;
    text-shadow: 0 2px 10px rgba(0,0,0,0.2);
    animation: fadeInUp 0.8s ease 0.1s both;
}

.hero .subtitle {
    font-size: 1.5rem;
    font-weight: 300;
    margin-bottom: 0.5rem;
    opacity: 0.9;
    animation: fadeInUp 0.8s ease 0.2s both;
}

.hero .description {
    font-size: 1.1rem;
    line-height: 1.8;
    opacity: 0.85;
    margin-bottom: 2rem;
    animation: fadeInUp 0.8s ease 0.3s both;
}

.cta-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    animation: fadeInUp 0.8s ease 0.4s both;
}

.btn {
    padding: 0.85rem 2rem;
    border-radius: 50px;
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
    cursor: pointer;
}

.btn-primary {
    background: white;
    color: var(--primary);
    box-shadow: 0 4px 15px rgba(0,0,0,0.15);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.2);
    color: var(--primary-dark);
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid rgba(255,255,255,0.6);
}

.btn-secondary:hover {
    background: rgba(255,255,255,0.1);
    border-color: white;
    color: white;
    transform: translateY(-2px);
}

/* ========== 通用区块 ========== */
.section {
    padding: 5rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.section-alt {
    background: var(--card-bg);
    max-width: 100%;
    border-radius: 0;
}

.section-alt > * {
    max-width: 1200px;
    margin-left: auto;
    margin-right: auto;
}

.section-title {
    text-align: center;
    font-size: 2.2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    margin: 0.8rem auto 0;
    border-radius: 2px;
}

.section-subtitle {
    text-align: center;
    color: var(--gray);
    font-size: 1.05rem;
    margin-bottom: 3rem;
    margin-top: 0.5rem;
}

/* ========== 关于我们 ========== */
.about-grid {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 3rem;
    align-items: center;
    margin-top: 2rem;
}

.about-text h3 {
    font-size: 1.8rem;
    color: var(--primary);
    margin-bottom: 1rem;
    font-weight: 700;
}

.about-text p {
    font-size: 1.05rem;
    color: var(--dark-secondary);
    margin-bottom: 1rem;
    line-height: 1.8;
}

.about-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1rem;
    margin-top: 2rem;
}

.stat-card {
    background: var(--bg);
    padding: 1.2rem 0.8rem;
    border-radius: var(--radius-sm);
    text-align: center;
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow);
}

.stat-number {
    font-size: 1.3rem;
    font-weight: 800;
    color: var(--primary);
    margin-bottom: 0.3rem;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--gray);
}

.about-image {
    text-align: center;
}

.about-image img {
    width: 100%;
    max-width: 300px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.about-image img:hover {
    transform: scale(1.03);
    box-shadow: var(--shadow-hover);
}

.about-image-caption {
    margin-top: 1rem;
    color: var(--gray);
    font-size: 0.95rem;
}

/* ========== 部门介绍 ========== */
.dept-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
}

.dept-card {
    background: var(--bg);
    border-radius: var(--radius);
    padding: 2rem;
    transition: var(--transition);
    border: 1px solid transparent;
}

.dept-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
    border-color: var(--primary-light);
}

.dept-icon {
    width: 56px;
    height: 56px;
    border-radius: 14px;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

.dept-icon i {
    font-size: 1.4rem;
    color: white;
}

.dept-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 0.5rem;
}

.dept-card p {
    font-size: 0.95rem;
    color: var(--gray);
    line-height: 1.7;
}

/* ========== 团队成员 ========== */
.team-group {
    margin-bottom: 3rem;
}

.team-group:last-child {
    margin-bottom: 0;
}

.team-group-title {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--dark-secondary);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.team-group-title i {
    color: var(--primary);
}

.team-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 1.2rem;
}

.team-grid-single {
    grid-template-columns: 200px;
}

.team-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 1.5rem 1rem;
    text-align: center;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.team-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.teacher-card {
    border: 2px solid var(--primary-light);
}

.team-avatar {
    width: 64px;
    height: 64px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 0.8rem;
}

.team-avatar i {
    font-size: 1.5rem;
    color: white;
}

.team-card h4 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 0.3rem;
}

.team-role {
    display: inline-block;
    font-size: 0.8rem;
    color: var(--primary);
    background: rgba(74, 144, 226, 0.1);
    padding: 0.2rem 0.8rem;
    border-radius: 50px;
    font-weight: 500;
}

.team-title {
    display: block;
    font-size: 0.85rem;
    color: var(--gray);
    margin-top: 0.3rem;
}

/* ========== 活动风采 ========== */
.activity-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
}

.activity-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.activity-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.activity-image {
    width: 100%;
    height: 220px;
    overflow: hidden;
}

.activity-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.activity-card:hover .activity-image img {
    transform: scale(1.05);
}

.activity-content {
    padding: 1.2rem 1.5rem 1.5rem;
}

.activity-tag {
    display: inline-block;
    font-size: 0.75rem;
    color: var(--accent-dark);
    background: rgba(72, 187, 120, 0.1);
    padding: 0.2rem 0.7rem;
    border-radius: 50px;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.activity-content h3 {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 0.4rem;
}

.activity-content p {
    font-size: 0.9rem;
    color: var(--gray);
    line-height: 1.6;
}

/* ========== 加入我们 ========== */
.join-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2.5rem;
    align-items: start;
}

.join-info h3,
.join-ways h3 {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.join-info h3 i {
    color: var(--primary);
}

.join-ways h3 i {
    color: var(--accent);
}

.join-item {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    align-items: flex-start;
}

.join-item-icon {
    width: 44px;
    height: 44px;
    min-width: 44px;
    border-radius: 12px;
    background: rgba(74, 144, 226, 0.1);
    display: flex;
    align-items: center;
    justify-content: center;
}

.join-item-icon i {
    font-size: 1.1rem;
    color: var(--primary);
}

.join-item h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 0.2rem;
}

.join-item p {
    font-size: 0.9rem;
    color: var(--gray);
    line-height: 1.6;
}

.join-ways {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.join-card {
    background: var(--bg);
    border-radius: var(--radius);
    padding: 1.5rem;
    text-align: center;
    transition: var(--transition);
}

.join-card:hover {
    box-shadow: var(--shadow);
}

.join-card-header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 1rem;
}

.join-card-header i {
    color: var(--primary);
    font-size: 1.3rem;
}

.join-card-qr {
    width: 180px;
    height: 180px;
    margin: 0 auto 1rem;
    border-radius: var(--radius-sm);
    overflow: hidden;
    background: white;
    padding: 8px;
    box-shadow: var(--shadow);
}

.join-card-qr img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 8px;
}

.join-card-info {
    font-size: 0.95rem;
    color: var(--gray);
}

.join-card-info strong {
    color: var(--dark);
}

.join-card-info a {
    color: var(--primary);
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: 0.3rem;
}

.join-card-info a:hover {
    color: var(--primary-dark);
}

/* ========== 联系方式 ========== */
.contact-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    margin-top: 2rem;
}

.contact-card {
    background: var(--bg);
    border-radius: var(--radius);
    padding: 2rem;
    text-align: center;
    transition: var(--transition);
}

.contact-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow);
}

.contact-icon {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
}

.contact-icon i {
    font-size: 1.3rem;
    color: white;
}

.contact-card h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 0.5rem;
}

.contact-card p,
.contact-card a {
    font-size: 0.95rem;
    color: var(--gray);
}

.contact-card a:hover {
    color: var(--primary);
}

/* ========== 页脚 ========== */
footer {
    background: linear-gradient(135deg, var(--dark), #0f172a);
    color: white;
    padding: 3rem 2rem 0;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    margin-bottom: 0.8rem;
}

.footer-brand img {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    object-fit: cover;
}

.footer-brand span {
    font-size: 1.2rem;
    font-weight: 700;
}

.footer-desc {
    font-size: 0.9rem;
    opacity: 0.7;
    line-height: 1.6;
}

.footer-links h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.footer-links a {
    display: block;
    color: rgba(255,255,255,0.7);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
    transition: var(--transition);
}

.footer-links a:hover {
    color: white;
    padding-left: 0.3rem;
}

.footer-bottom {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1.5rem 0;
    text-align: center;
}

.footer-bottom p {
    font-size: 0.85rem;
    opacity: 0.5;
}

/* ========== 回到顶部 ========== */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--primary);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    box-shadow: 0 4px 15px rgba(74, 144, 226, 0.3);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: var(--transition);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

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

/* ========== 动画 ========== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(25px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animate-in {
    opacity: 0;
    transform: translateY(25px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.animate-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
    .dept-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .nav-container {
        padding: 0.6rem 1.2rem;
    }

    .menu-toggle {
        display: block;
    }

    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 0.8rem;
        box-shadow: 0 10px 30px rgba(0,0,0,0.1);
        gap: 0.2rem;
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-menu a {
        padding: 0.8rem 1rem;
        border-radius: 8px;
    }

    .hero {
        min-height: 85vh;
        padding: 2rem 1rem;
    }

    .hero h1 {
        font-size: 2.2rem;
    }

    .hero .subtitle {
        font-size: 1.2rem;
    }

    .hero .description {
        font-size: 1rem;
    }

    .cta-buttons {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        max-width: 280px;
        justify-content: center;
    }

    .section {
        padding: 3rem 1.2rem;
    }

    .section-title {
        font-size: 1.8rem;
    }

    .about-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .about-stats {
        grid-template-columns: repeat(2, 1fr);
    }

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

    .team-grid {
        grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
    }

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

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

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

    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .footer-brand {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 1.8rem;
    }

    .section-title {
        font-size: 1.5rem;
    }

    .about-stats {
        grid-template-columns: repeat(2, 1fr);
    }

    .join-card-qr {
        width: 160px;
        height: 160px;
    }
}