/* ========================================
   全局样式与变量
   ======================================== */
:root {
    /* 主题色 - 农业绿色系 */
    --primary-color: #2e7d32;
    --primary-light: #4caf50;
    --primary-dark: #1b5e20;
    --secondary-color: #81c784;
    
    /* 辅助色 */
    --accent-color: #ff9800;
    --text-color: #333;
    --text-light: #666;
    --text-muted: #999;
    --bg-color: #f8f9fa;
    --white: #ffffff;
    --border-color: #e0e0e0;
    
    /* 字体 */
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
    
    /* 阴影 */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.15);
    
    /* 圆角 */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 20px;
    
    /* 过渡 */
    --transition: all 0.3s ease;
}

/* 重置样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--white);
    overflow-x: hidden;
}

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

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

ul, ol {
    list-style: none;
}

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
}

/* 容器 */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ========================================
   头部样式
   ======================================== */
.header {
    background: var(--white);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.header-top {
    padding: 15px 0;
    border-bottom: 1px solid var(--border-color);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 15px;
}

.logo img {
    height: 60px;
    width: auto;
}

.logo-text h1 {
    font-size: 24px;
    font-weight: 600;
    color: var(--primary-color);
    line-height: 1.3;
}

.logo-text p {
    font-size: 12px;
    color: var(--text-light);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 20px;
}

.search-box {
    position: relative;
    display: flex;
    align-items: center;
}

.search-input {
    width: 240px;
    padding: 8px 45px 8px 15px;
    border: 1px solid var(--border-color);
    border-radius: 25px;
    font-size: 14px;
    outline: none;
    transition: var(--transition);
}

.search-input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(46, 125, 50, 0.1);
}

.search-btn {
    position: absolute;
    right: 5px;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
    transition: var(--transition);
}

.search-btn:hover {
    background: var(--primary-color);
    color: var(--white);
}

/* 导航栏 */
.nav {
    background: var(--primary-color);
}

.nav-wrapper {
    position: relative;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: space-around;
    width: 30px;
    height: 24px;
    padding: 5px 0;
}

.nav-toggle span {
    display: block;
    width: 100%;
    height: 3px;
    background: var(--white);
    border-radius: 2px;
    transition: var(--transition);
}

.nav-menu {
    display: flex;
    align-items: center;
}

.nav-item {
    position: relative;
}

.nav-link {
    display: block;
    padding: 15px 25px;
    color: var(--white);
    font-size: 16px;
    font-weight: 500;
    transition: var(--transition);
}

.nav-link:hover,
.nav-item.active .nav-link {
    background: rgba(255, 255, 255, 0.15);
}

/* 下拉菜单 */
.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 180px;
    background: var(--white);
    box-shadow: var(--shadow-lg);
    border-radius: 0 0 var(--radius-md) var(--radius-md);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: var(--transition);
    z-index: 100;
}

.nav-item:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu li a {
    display: block;
    padding: 12px 20px;
    color: var(--text-color);
    font-size: 14px;
    border-bottom: 1px solid var(--border-color);
}

.dropdown-menu li:last-child a {
    border-bottom: none;
}

.dropdown-menu li a:hover {
    background: var(--bg-color);
    color: var(--primary-color);
    padding-left: 25px;
}

/* ========================================
   Hero Banner 样式
   ======================================== */
.hero-section {
    position: relative;
    height: 100vh;
    min-height: 600px;
    max-height: 900px;
    margin-top: 120px;
}

.hero-swiper {
    width: 100%;
    height: 100%;
}

.hero-slide {
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    position: relative;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(27, 94, 32, 0.85) 0%, rgba(46, 125, 50, 0.75) 100%);
}

.hero-content {
    position: relative;
    z-index: 10;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    color: var(--white);
    padding: 20px;
}

.hero-title {
    font-size: 56px;
    font-weight: 700;
    margin-bottom: 15px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.hero-subtitle {
    font-size: 24px;
    font-weight: 300;
    margin-bottom: 20px;
    opacity: 0.9;
}

.hero-desc {
    font-size: 18px;
    max-width: 600px;
    margin-bottom: 30px;
    opacity: 0.85;
}

.hero-btn {
    display: inline-block;
    padding: 15px 40px;
    background: var(--accent-color);
    color: var(--white);
    font-size: 16px;
    font-weight: 600;
    border-radius: 30px;
    transition: var(--transition);
}

.hero-btn:hover {
    background: #f57c00;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 152, 0, 0.4);
}

/* Swiper 控制按钮 */
.hero-swiper .swiper-button-prev,
.hero-swiper .swiper-button-next {
    width: 50px;
    height: 50px;
    background: rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    transition: var(--transition);
}

.hero-swiper .swiper-button-prev:hover,
.hero-swiper .swiper-button-next:hover {
    background: rgba(255, 255, 255, 0.5);
}

.hero-swiper .swiper-button-prev::after,
.hero-swiper .swiper-button-next::after {
    font-size: 20px;
    color: var(--white);
}

.hero-swiper .swiper-pagination-bullet {
    width: 12px;
    height: 12px;
    background: var(--white);
    opacity: 0.5;
}

.hero-swiper .swiper-pagination-bullet-active {
    opacity: 1;
    background: var(--accent-color);
}

/* 滚动指示器 */
.scroll-down {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 10;
}

.scroll-down span {
    display: block;
    width: 24px;
    height: 40px;
    border: 2px solid var(--white);
    border-radius: 12px;
    position: relative;
}

.scroll-down span::before {
    content: '';
    position: absolute;
    top: 8px;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 8px;
    background: var(--white);
    border-radius: 2px;
    animation: scroll 2s infinite;
}

@keyframes scroll {
    0% {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
    100% {
        opacity: 0;
        transform: translateX(-50%) translateY(15px);
    }
}

/* 动画 */
.animate-fadeInUp {
    animation: fadeInUp 0.8s ease forwards;
    opacity: 0;
}

.delay-1 { animation-delay: 0.2s; }
.delay-2 { animation-delay: 0.4s; }
.delay-3 { animation-delay: 0.6s; }

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ========================================
   统计数据样式
   ======================================== */
.stats-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    padding: 60px 0;
    color: var(--white);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
}

.stat-item {
    text-align: center;
    padding: 20px;
}

.stat-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 15px;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.stat-icon svg {
    width: 32px;
    height: 32px;
    stroke: var(--white);
}

.stat-number {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 5px;
}

.stat-label {
    font-size: 16px;
    opacity: 0.9;
}

/* ========================================
   通用区块标题
   ======================================== */
.section-header {
    text-align: center;
    margin-bottom: 50px;
}

.section-title {
    font-size: 36px;
    font-weight: 700;
    color: var(--text-color);
    margin-bottom: 10px;
}

.section-subtitle {
    font-size: 14px;
    color: var(--primary-color);
    text-transform: uppercase;
    letter-spacing: 3px;
}

/* ========================================
   研究院概况
   ======================================== */
.about-section {
    padding: 80px 0;
    background: var(--white);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 50px;
    align-items: center;
}

.about-image {
    position: relative;
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.about-image img {
    width: 100%;
    height: 400px;
    object-fit: cover;
    transition: var(--transition);
}

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

.about-image-overlay {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(to top, rgba(0,0,0,0.7), transparent);
    padding: 30px;
}

.about-badge {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    background: var(--accent-color);
    padding: 20px 30px;
    border-radius: var(--radius-md);
}

.badge-number {
    font-size: 36px;
    font-weight: 700;
    color: var(--white);
}

.badge-text {
    font-size: 14px;
    color: var(--white);
}

.about-text h3 {
    font-size: 28px;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.about-text p {
    font-size: 15px;
    line-height: 1.8;
    color: var(--text-light);
    margin-bottom: 15px;
}

.about-features {
    margin-top: 25px;
}

.feature-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
}

.feature-item:last-child {
    border-bottom: none;
}

.feature-icon {
    width: 24px;
    height: 24px;
    background: var(--primary-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.feature-icon svg {
    width: 14px;
    height: 14px;
    stroke: var(--white);
    stroke-width: 3;
}

.feature-item span {
    font-size: 15px;
    color: var(--text-color);
}

/* ========================================
   研究方向
   ======================================== */
.research-section {
    padding: 80px 0;
    background: var(--bg-color);
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
}

.research-card {
    background: var(--white);
    padding: 35px 25px;
    border-radius: var(--radius-lg);
    text-align: center;
    transition: var(--transition);
    border: 1px solid transparent;
}

.research-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-light);
}

.research-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 20px;
    background: linear-gradient(135deg, var(--primary-light), var(--primary-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.research-card:hover .research-icon {
    transform: rotateY(180deg);
}

.research-icon svg {
    width: 40px;
    height: 40px;
    stroke: var(--white);
}

.research-card h3 {
    font-size: 20px;
    color: var(--text-color);
    margin-bottom: 15px;
}

.research-card p {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.6;
    margin-bottom: 20px;
}

.research-link {
    color: var(--primary-color);
    font-size: 14px;
    font-weight: 500;
}

.research-link:hover {
    color: var(--primary-dark);
}

/* ========================================
   新闻动态
   ======================================== */
.news-section {
    padding: 80px 0;
    background: var(--white);
}

.news-tabs {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 40px;
}

.news-tab {
    padding: 10px 25px;
    background: var(--bg-color);
    color: var(--text-color);
    border-radius: 25px;
    font-size: 15px;
    font-weight: 500;
    transition: var(--transition);
}

.news-tab:hover,
.news-tab.active {
    background: var(--primary-color);
    color: var(--white);
}

.news-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}

.news-card {
    background: var(--white);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

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

.news-card.featured {
    grid-column: 1 / 2;
    grid-row: 1 / 3;
}

.news-card.featured .news-image {
    height: 280px;
    position: relative;
}

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

.news-tag {
    position: absolute;
    top: 15px;
    left: 15px;
    padding: 5px 15px;
    background: var(--accent-color);
    color: var(--white);
    font-size: 12px;
    font-weight: 600;
    border-radius: 15px;
}

.news-content {
    padding: 25px;
}

.news-meta {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 12px;
    font-size: 13px;
    color: var(--text-muted);
}

.news-date {
    display: flex;
    align-items: center;
    gap: 5px;
}

.news-date svg {
    width: 14px;
    height: 14px;
}

.news-category {
    padding: 3px 10px;
    background: var(--bg-color);
    border-radius: 10px;
    color: var(--primary-color);
    font-weight: 500;
}

.news-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 10px;
    line-height: 1.5;
    transition: var(--transition);
}

.news-card:hover .news-title {
    color: var(--primary-color);
}

.news-excerpt {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.6;
    margin-bottom: 15px;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.news-link {
    color: var(--primary-color);
    font-size: 14px;
    font-weight: 500;
}

.news-link:hover {
    color: var(--primary-dark);
}

.news-more {
    text-align: center;
    margin-top: 40px;
}

.btn {
    display: inline-block;
    padding: 12px 35px;
    border-radius: 25px;
    font-size: 15px;
    font-weight: 600;
    transition: var(--transition);
}

.btn-primary {
    background: var(--primary-color);
    color: var(--white);
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(46, 125, 50, 0.3);
}

/* ========================================
   科研成果
   ======================================== */
.achievements-section {
    padding: 80px 0;
    background: var(--bg-color);
}

.achievements-slider {
    padding: 0 0 50px;
}

.achievement-card {
    background: var(--white);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

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

.achievement-image {
    height: 200px;
    overflow: hidden;
}

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

.achievement-card:hover .achievement-image img {
    transform: scale(1.1);
}

.achievement-content {
    padding: 25px;
}

.achievement-content h4 {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 10px;
}

.achievement-content p {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.6;
    margin-bottom: 15px;
}

.achievement-tag {
    display: inline-block;
    padding: 5px 12px;
    background: linear-gradient(135deg, var(--primary-light), var(--primary-color));
    color: var(--white);
    font-size: 12px;
    border-radius: 15px;
}

.achievements-swiper .swiper-pagination {
    bottom: 0;
}

.achievements-swiper .swiper-pagination-bullet {
    width: 10px;
    height: 10px;
    background: var(--primary-color);
    opacity: 0.3;
}

.achievements-swiper .swiper-pagination-bullet-active {
    opacity: 1;
}

/* ========================================
   合作单位
   ======================================== */
.partners-section {
    padding: 80px 0;
    background: var(--white);
}

.partners-grid {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 30px;
    align-items: center;
}

.partner-item {
    background: var(--bg-color);
    padding: 20px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100px;
    transition: var(--transition);
}

.partner-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-3px);
}

.partner-item img {
    max-width: 100%;
    max-height: 60px;
    filter: grayscale(100%);
    opacity: 0.6;
    transition: var(--transition);
}

.partner-item:hover img {
    filter: grayscale(0);
    opacity: 1;
}

.partner-placeholder {
    width: 100%;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-light), var(--primary-color));
    color: var(--white);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    font-weight: 500;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.partner-item:hover .partner-placeholder {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    transform: scale(1.05);
}

/* ========================================
   联系我们
   ======================================== */
.contact-section {
    padding: 80px 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: var(--white);
}

.contact-section .section-title,
.contact-section .section-subtitle {
    color: var(--white);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 50px;
}

.contact-info {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
}

.contact-item {
    display: flex;
    gap: 15px;
}

.contact-icon {
    width: 50px;
    height: 50px;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.contact-icon svg {
    width: 24px;
    height: 24px;
    stroke: var(--white);
}

.contact-text h4 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 5px;
}

.contact-text p {
    font-size: 14px;
    opacity: 0.9;
}

.contact-map {
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    overflow: hidden;
    min-height: 300px;
}

.map-placeholder {
    width: 100%;
    height: 300px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    opacity: 0.5;
}

.map-placeholder svg {
    width: 60px;
    height: 60px;
    margin-bottom: 15px;
}

/* ========================================
   页脚
   ======================================== */
.footer {
    background: #1a1a1a;
    color: var(--white);
    padding-top: 60px;
}

.footer-top {
    display: grid;
    grid-template-columns: 1.5fr 2fr;
    gap: 50px;
    padding-bottom: 40px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 20px;
}

.footer-logo img {
    height: 50px;
}

.footer-logo h3 {
    font-size: 20px;
    font-weight: 600;
}

.footer-info p {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.7);
    line-height: 1.8;
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.footer-column h4 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 20px;
    position: relative;
}

.footer-column h4::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    width: 30px;
    height: 2px;
    background: var(--primary-color);
}

.footer-column ul li {
    margin-bottom: 12px;
}

.footer-column ul li a {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.7);
    transition: var(--transition);
}

.footer-column ul li a:hover {
    color: var(--primary-light);
    padding-left: 5px;
}

.footer-bottom {
    padding: 25px 0;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
    text-align: center; 
}

.copyright p {
    text-align: center;
    font-size: 13px;
    color: rgba(255, 255, 255, 0.6);
    line-height: 1.8;
}

.footer-beian a {
    text-align: center;
    font-size: 13px;
    color: rgba(255, 255, 255, 0.6);
}

.footer-beian a:hover {
    text-align: center;
    color: var(--primary-light);
}

/* ========================================
   返回顶部
   ======================================== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
}

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

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

.back-to-top svg {
    width: 24px;
    height: 24px;
}

/* ========================================
   响应式设计
   ======================================== */
@media screen and (max-width: 1200px) {
    .container {
        max-width: 960px;
    }
    
    .research-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .partners-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

@media screen and (max-width: 992px) {
    .container {
        max-width: 720px;
    }
    
    .header-content {
        flex-wrap: wrap;
    }
    
    .logo-text h1 {
        font-size: 20px;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--primary-color);
        flex-direction: column;
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease;
    }
    
    .nav-menu.active {
        max-height: 500px;
    }
    
    .nav-link {
        padding: 12px 20px;
        border-top: 1px solid rgba(255, 255, 255, 0.1);
    }
    
    .dropdown-menu {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        background: rgba(0, 0, 0, 0.1);
        box-shadow: none;
        border-radius: 0;
        display: none;
    }
    
    .nav-item:hover .dropdown-menu {
        display: block;
    }
    
    .dropdown-menu li a {
        color: var(--white);
        border-bottom-color: rgba(255, 255, 255, 0.1);
        padding-left: 40px;
    }
    
    .hero-title {
        font-size: 42px;
    }
    
    .hero-subtitle {
        font-size: 18px;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .about-image img {
        height: 300px;
    }
    
    .news-grid {
        grid-template-columns: 1fr;
    }
    
    .news-card.featured {
        grid-column: auto;
        grid-row: auto;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .footer-top {
        grid-template-columns: 1fr;
    }
    
    .footer-links {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media screen and (max-width: 768px) {
    .hero-section {
        margin-top: 100px;
        min-height: 500px;
    }
    
    .hero-title {
        font-size: 32px;
    }
    
    .hero-subtitle {
        font-size: 16px;
    }
    
    .hero-desc {
        font-size: 14px;
    }
    
    .hero-swiper .swiper-button-prev,
    .hero-swiper .swiper-button-next {
        display: none;
    }
    
    .section-title {
        font-size: 28px;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
    }
    
    .stat-number {
        font-size: 36px;
    }
    
    .research-grid {
        grid-template-columns: 1fr;
    }
    
    .news-tabs {
        flex-wrap: wrap;
    }
    
    .partners-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .contact-info {
        grid-template-columns: 1fr;
    }
    
    .footer-links {
        grid-template-columns: 1fr;
    }
    
    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
}

@media screen and (max-width: 576px) {
    .container {
        padding: 0 15px;
    }
    
    .header-top {
        padding: 10px 0;
    }
    
    .logo img {
        height: 45px;
    }
    
    .logo-text h1 {
        font-size: 16px;
    }
    
    .logo-text p {
        font-size: 10px;
    }
    
    .search-input {
        width: 180px;
    }
    
    .hero-title {
        font-size: 26px;
    }
    
    .hero-btn {
        padding: 12px 30px;
        font-size: 14px;
    }
    
    .stat-item {
        padding: 15px;
    }
    
    .stat-number {
        font-size: 28px;
    }
    
    .about-text h3 {
        font-size: 22px;
    }
    
    .back-to-top {
        width: 45px;
        height: 45px;
        bottom: 20px;
        right: 20px;
    }
}

/* ========================================
   打印样式
   ======================================== */
@media print {
    .header,
    .hero-section,
    .back-to-top,
    .scroll-down {
        display: none;
    }
    
    body {
        color: #000;
        background: #fff;
    }
    
    .section-title {
        color: #000;
    }
}