/* ===== CSS 变量与全局 ===== */
:root {
    --primary: #0a2f6c;
    --primary-light: #1a4a8a;
    --primary-dark: #061f4a;
    --accent: #c0392b;
    --accent-light: #e74c3c;
    --gold: #d4a017;
    --gold-light: #f0c040;
    --bg-light: #f8f9fc;
    --bg-dark: #0b1a30;
    --text-dark: #1e293b;
    --text-light: #f1f5f9;
    --text-muted: #64748b;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
    --shadow-md: 0 8px 30px rgba(0,0,0,0.12);
    --shadow-lg: 0 20px 60px rgba(0,0,0,0.15);
    --radius: 16px;
    --radius-sm: 8px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-serif: 'Noto Serif SC', Georgia, 'Times New Roman', serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    color: var(--text-dark);
    background: var(--bg-light);
    line-height: 1.7;
    overflow-x: hidden;
}

img {
    max-width: 100%;
    display: block;
}

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

ul {
    list-style: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== 按钮 ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 12px 28px;
    border-radius: 50px;
    font-weight: 600;
    font-size: 0.95rem;
    border: none;
    cursor: pointer;
    transition: var(--transition);
    letter-spacing: 0.5px;
}

.btn-primary {
    background: var(--primary);
    color: white;
    box-shadow: 0 4px 15px rgba(10, 47, 108, 0.3);
}

.btn-primary:hover {
    background: var(--primary-light);
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(10, 47, 108, 0.4);
}

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

.btn-secondary:hover {
    background: rgba(255,255,255,0.15);
    border-color: white;
    transform: translateY(-3px);
}

.btn-primary-outline {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
}

.btn-primary-outline:hover {
    background: var(--primary);
    color: white;
    transform: translateY(-3px);
}

.btn-full {
    width: 100%;
    justify-content: center;
}

/* ===== 头部导航 ===== */
#header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: 16px 0;
    transition: var(--transition);
    background: transparent;
}

#header.scrolled {
    background: rgba(255,255,255,0.92);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    box-shadow: 0 2px 20px rgba(0,0,0,0.08);
    padding: 10px 0;
}

#header.scrolled .logo-text {
    color: var(--primary);
}

#header.scrolled .nav-list a {
    color: var(--text-dark);
}

#header.scrolled .nav-list a:hover,
#header.scrolled .nav-list a.active {
    color: var(--accent);
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo a {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo-icon {
    font-size: 1.8rem;
    color: var(--gold-light);
    background: rgba(212, 160, 23, 0.15);
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 12px;
    transition: var(--transition);
}

.logo-text {
    font-family: var(--font-serif);
    font-size: 1.4rem;
    font-weight: 700;
    color: white;
    letter-spacing: 2px;
    transition: var(--transition);
}

.nav-list {
    display: flex;
    gap: 8px;
}

.nav-list a {
    color: rgba(255,255,255,0.85);
    padding: 8px 16px;
    border-radius: 30px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition);
}

.nav-list a:hover,
.nav-list a.active {
    color: white;
    background: rgba(255,255,255,0.12);
}

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 8px;
    border-radius: 8px;
    background: rgba(255,255,255,0.1);
}

.hamburger span {
    display: block;
    width: 28px;
    height: 2.5px;
    background: white;
    border-radius: 4px;
    transition: var(--transition);
}

.hamburger.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}
.hamburger.active span:nth-child(2) {
    opacity: 0;
}
.hamburger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* ===== Hero 区 ===== */
.hero-section {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #0a1e3d 0%, #1a3a6b 40%, #2a4a7a 70%, #0f2d5a 100%);
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 50%, rgba(212,160,23,0.08) 0%, transparent 50%),
                radial-gradient(circle at 70% 30%, rgba(10,47,108,0.3) 0%, transparent 50%);
    animation: heroGlow 15s ease-in-out infinite alternate;
}

@keyframes heroGlow {
    0% { transform: translate(0, 0) scale(1); }
    100% { transform: translate(5%, 5%) scale(1.1); }
}

.hero-overlay {
    position: absolute;
    inset: 0;
    background: url('data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iNjAiIGhlaWdodD0iNjAiIHZpZXdCb3g9IjAgMCA2MCA2MCIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj48ZyBmaWxsPSJub25lIiBmaWxsLXJ1bGU9ImV2ZW5vZGQiPjxnIGZpbGw9IiNmZmYiIGZpbGwtb3BhY2l0eT0iMC4wMyI+PHBhdGggZD0iTTM2IDM0djItSDI0di0yaDEyek0zNiAyNHYySDI0di0yaDEyeiIvPjwvZz48L2c+PC9zdmc+');
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    padding: 120px 24px 80px;
    max-width: 900px;
}

.hero-badge {
    display: inline-block;
    background: rgba(212,160,23,0.2);
    border: 1px solid rgba(212,160,23,0.3);
    color: var(--gold-light);
    padding: 6px 20px;
    border-radius: 50px;
    font-size: 0.85rem;
    letter-spacing: 2px;
    margin-bottom: 24px;
    backdrop-filter: blur(4px);
}

.hero-content h1 {
    font-family: var(--font-serif);
    font-size: clamp(2.8rem, 8vw, 5rem);
    color: white;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 20px;
}

.hero-content h1 .highlight {
    background: linear-gradient(135deg, var(--gold-light), #f5d76e);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.15rem;
    color: rgba(255,255,255,0.7);
    max-width: 600px;
    margin: 0 auto 40px;
    line-height: 1.8;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 40px;
    flex-wrap: wrap;
    margin-bottom: 48px;
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-family: var(--font-serif);
    font-size: 2.4rem;
    font-weight: 700;
    color: var(--gold-light);
    line-height: 1.2;
}

.stat-label {
    font-size: 0.85rem;
    color: rgba(255,255,255,0.6);
    letter-spacing: 1px;
}

.hero-actions {
    display: flex;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
}

.scroll-indicator {
    position: absolute;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: rgba(255,255,255,0.4);
    font-size: 0.8rem;
    animation: bounceDown 2s infinite;
    z-index: 2;
}

@keyframes bounceDown {
    0%, 100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(10px); }
}

/* ===== 通用 section ===== */
.section {
    padding: 100px 0;
}

.section-light {
    background: var(--bg-light);
}

.section-dark {
    background: var(--bg-dark);
    color: var(--text-light);
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-tag {
    display: inline-block;
    font-size: 0.8rem;
    letter-spacing: 3px;
    text-transform: uppercase;
    color: var(--accent);
    font-weight: 600;
    margin-bottom: 12px;
}

.section-dark .section-tag {
    color: var(--gold-light);
}

.section-header h2 {
    font-family: var(--font-serif);
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 700;
    margin-bottom: 16px;
}

.section-dark .section-header h2 {
    color: white;
}

.section-desc {
    color: var(--text-muted);
    max-width: 500px;
    margin: 0 auto;
    font-size: 1.05rem;
}

.section-dark .section-desc {
    color: rgba(255,255,255,0.6);
}

/* ===== 关于川大 ===== */
.about-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 28px;
    margin-bottom: 48px;
}

.about-card {
    background: white;
    padding: 36px 28px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 1px solid rgba(0,0,0,0.04);
    text-align: center;
}

.about-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-md);
}

.card-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 1.6rem;
    color: white;
    transition: var(--transition);
}

.about-card:hover .card-icon {
    transform: scale(1.1) rotate(-5deg);
}

.about-card h3 {
    font-family: var(--font-serif);
    font-size: 1.25rem;
    margin-bottom: 12px;
    color: var(--primary-dark);
}

.about-card p {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.7;
}

.about-quote {
    max-width: 700px;
    margin: 0 auto;
    text-align: center;
}

.about-quote blockquote {
    font-family: var(--font-serif);
    font-size: 1.5rem;
    color: var(--primary);
    font-style: italic;
    padding: 24px 0;
    border-top: 2px solid rgba(10, 47, 108, 0.1);
    border-bottom: 2px solid rgba(10, 47, 108, 0.1);
    line-height: 1.6;
}

/* ===== 学术科研 ===== */
.academics-filter {
    display: flex;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
    margin-bottom: 40px;
}

.filter-btn {
    padding: 10px 24px;
    border-radius: 50px;
    border: 1px solid rgba(255,255,255,0.2);
    background: transparent;
    color: rgba(255,255,255,0.7);
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.filter-btn:hover {
    background: rgba(255,255,255,0.08);
    color: white;
}

.filter-btn.active {
    background: var(--gold);
    color: var(--bg-dark);
    border-color: var(--gold);
    font-weight: 600;
}

.academics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 24px;
}

.academic-card {
    background: rgba(255,255,255,0.05);
    border: 1px solid rgba(255,255,255,0.08);
    border-radius: var(--radius);
    padding: 28px;
    transition: var(--transition);
    backdrop-filter: blur(4px);
}

.academic-card:hover {
    background: rgba(255,255,255,0.1);
    transform: translateY(-6px);
    border-color: rgba(212,160,23,0.3);
    box-shadow: 0 12px 40px rgba(0,0,0,0.2);
}

.academic-card .card-icon {
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--gold), var(--gold-light));
    border-radius: 14px;
    font-size: 1.3rem;
    margin: 0 0 16px;
}

.academic-card h3 {
    font-family: var(--font-serif);
    font-size: 1.15rem;
    margin-bottom: 8px;
    color: white;
}

.academic-card .category-tag {
    display: inline-block;
    font-size: 0.75rem;
    padding: 3px 12px;
    border-radius: 20px;
    background: rgba(212,160,23,0.15);
    color: var(--gold-light);
    margin-bottom: 12px;
}

.academic-card p {
    color: rgba(255,255,255,0.6);
    font-size: 0.9rem;
    line-height: 1.6;
}

/* ===== 校园文化 ===== */
.campus-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.campus-item {
    border-radius: var(--radius);
    overflow: hidden;
    position: relative;
    aspect-ratio: 3 / 2;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.campus-item:hover {
    transform: scale(1.02);
    box-shadow: var(--shadow-md);
}

.campus-image {
    width: 100%;
    height: 100%;
    position: relative;
}

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

.campus-item:hover .campus-image img {
    transform: scale(1.1);
}

.campus-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(to top, rgba(10, 30, 61, 0.85) 0%, transparent 60%);
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    padding: 24px;
    transition: var(--transition);
}

.campus-overlay h3 {
    font-family: var(--font-serif);
    color: white;
    font-size: 1.3rem;
    margin-bottom: 6px;
}

.campus-overlay p {
    color: rgba(255,255,255,0.7);
    font-size: 0.9rem;
}

/* ===== 新闻动态 ===== */
.news-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 28px;
    margin-bottom: 48px;
}

.news-card {
    background: rgba(255,255,255,0.04);
    border: 1px solid rgba(255,255,255,0.08);
    border-radius: var(--radius);
    overflow: hidden;
    transition: var(--transition);
}

.news-card:hover {
    transform: translateY(-6px);
    background: rgba(255,255,255,0.07);
    border-color: rgba(212,160,23,0.2);
    box-shadow: 0 12px 40px rgba(0,0,0,0.15);
}

.news-image {
    height: 180px;
    overflow: hidden;
}

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

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

.news-body {
    padding: 24px;
}

.news-date {
    font-size: 0.8rem;
    color: rgba(255,255,255,0.4);
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.news-body h3 {
    font-family: var(--font-serif);
    font-size: 1.1rem;
    margin-bottom: 10px;
    color: white;
    line-height: 1.4;
}

.news-body p {
    color: rgba(255,255,255,0.55);
    font-size: 0.9rem;
    line-height: 1.6;
}

.news-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    color: var(--gold-light);
    font-size: 0.9rem;
    font-weight: 500;
    margin-top: 12px;
    transition: var(--transition);
}

.news-link:hover {
    gap: 12px;
    color: white;
}

.news-more {
    text-align: center;
}

/* ===== 联系我们 ===== */
.contact-wrapper {
    display: grid;
    grid-template-columns: 1fr 1.2fr;
    gap: 48px;
    align-items: start;
}

.contact-info {
    display: grid;
    gap: 24px;
}

.info-item {
    display: flex;
    gap: 16px;
    align-items: flex-start;
    background: white;
    padding: 20px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.info-item:hover {
    transform: translateX(6px);
    box-shadow: var(--shadow-md);
}

.info-item i {
    font-size: 1.4rem;
    color: var(--primary);
    width: 44px;
    height: 44px;
    background: rgba(10, 47, 108, 0.06);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.info-item h4 {
    font-size: 1rem;
    color: var(--primary-dark);
    margin-bottom: 4px;
}

.info-item p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.contact-form {
    background: white;
    padding: 36px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
}

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 14px 18px;
    border: 1.5px solid #e2e8f0;
    border-radius: var(--radius-sm);
    font-family: var(--font-sans);
    font-size: 0.95rem;
    transition: var(--transition);
    outline: none;
    background: #f8fafc;
}

.contact-form input:focus,
.contact-form textarea:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(10, 47, 108, 0.08);
    background: white;
}

.contact-form .form-row {
    display: flex;
    gap: 16px;
    margin-bottom: 16px;
}

.contact-form input:not(.form-row input) {
    margin-bottom: 16px;
}

.contact-form textarea {
    margin-bottom: 20px;
    resize: vertical;
}

/* ===== 页脚 ===== */
#footer {
    background: var(--bg-dark);
    color: rgba(255,255,255,0.7);
    padding-top: 60px;
}

.footer-content {
    display: flex;
    flex-wrap: wrap;
    gap: 48px;
    justify-content: space-between;
    padding-bottom: 40px;
    border-bottom: 1px solid rgba(255,255,255,0.08);
}

.footer-brand {
    max-width: 260px;
}

.footer-brand .logo-icon {
    margin-bottom: 12px;
}

.footer-brand .logo-text {
    font-size: 1.5rem;
    color: white;
}

.footer-brand p {
    margin-top: 8px;
    color: rgba(255,255,255,0.4);
    font-size: 0.9rem;
}

.footer-social {
    display: flex;
    gap: 12px;
    margin-top: 20px;
}

.footer-social a {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: rgba(255,255,255,0.06);
    display: flex;
    align-items: center;
    justify-content: center;
    color: rgba(255,255,255,0.5);
    transition: var(--transition);
}

.footer-social a:hover {
    background: var(--gold);
    color: var(--bg-dark);
    transform: translateY(-3px);
}

.footer-links {
    display: flex;
    gap: 60px;
    flex-wrap: wrap;
}

.link-group h4 {
    color: white;
    font-size: 1rem;
    margin-bottom: 16px;
    font-weight: 600;
}

.link-group ul li {
    margin-bottom: 10px;
}

.link-group ul li a {
    color: rgba(255,255,255,0.5);
    font-size: 0.9rem;
    transition: var(--transition);
}

.link-group ul li a:hover {
    color: var(--gold-light);
    padding-left: 4px;
}

.footer-bottom {
    padding: 20px 0;
    text-align: center;
    font-size: 0.85rem;
    color: rgba(255,255,255,0.3);
}

/* ===== 回到顶部 ===== */
#back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--primary);
    color: white;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    box-shadow: var(--shadow-md);
    opacity: 0;
    transform: translateY(20px);
    transition: var(--transition);
    z-index: 999;
}

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

#back-to-top:hover {
    background: var(--primary-light);
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

/* ===== 响应式 ===== */
@media (max-width: 992px) {
    .contact-wrapper {
        grid-template-columns: 1fr;
    }
    .footer-content {
        flex-direction: column;
        gap: 36px;
    }
    .footer-links {
        gap: 32px;
    }
    .hero-stats {
        gap: 24px;
    }
    .stat-number {
        font-size: 2rem;
    }
}

@media (max-width: 768px) {
    .nav-list {
        position: fixed;
        top: 0;
        right: -100%;
        width: 280px;
        height: 100vh;
        background: rgba(10, 30, 61, 0.98);
        backdrop-filter: blur(20px);
        flex-direction: column;
        padding: 80px 32px 32px;
        transition: var(--transition);
        box-shadow: -10px 0 40px rgba(0,0,0,0.3);
        gap: 4px;
    }

    .nav-list.open {
        right: 0;
    }

    .nav-list a {
        color: rgba(255,255,255,0.7);
        font-size: 1.1rem;
        padding: 12px 16px;
        border-radius: 12px;
    }

    .nav-list a:hover {
        background: rgba(255,255,255,0.08);
        color: white;
    }

    .hamburger {
        display: flex;
    }

    .hero-content {
        padding: 100px 20px 60px;
    }

    .hero-content h1 {
        font-size: 2.6rem;
    }

    .hero-stats {
        gap: 16px;
    }

    .stat-item {
        flex: 1 1 40%;
    }

    .section {
        padding: 60px 0;
    }

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

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

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

    .contact-form {
        padding: 24px;
    }

    .contact-form .form-row {
        flex-direction: column;
    }

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

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

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

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

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

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

    .academics-filter {
        gap: 8px;
    }

    .filter-btn {
        padding: 8px 16px;
        font-size: 0.8rem;
    }

    #back-to-top {
        bottom: 20px;
        right: 20px;
        width: 42px;
        height: 42px;
        font-size: 1rem;
    }
}