/* 全局样式 - 学术风格 */
:root {
    --primary-color: #003366;
    --secondary-color: #8B0000;
    --light-bg: #f8f9fa;
    --dark-text: #333333;
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
}

body {
    font-family: 'Arial', sans-serif;
    line-height: 1.6;
    color: var(--dark-text);
    margin: 0;
    background-color: var(--light-bg);
}

/* 导航栏样式 */
.navbar {
    background-color: white;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    padding: 0;
}

.nav-item {
    margin-right: 2rem;
}

.nav-link {
    color: var(--dark-text);
    text-decoration: none;
    font-weight: 500;
    padding: 0.5rem 0;
    border-bottom: 2px solid transparent;
    transition: all 0.3s;
}

.nav-link:hover, .current-page {
    color: var(--primary-color);
    border-bottom: 2px solid var(--secondary-color);
}

/* 主要内容区 */
.main-container {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 2rem;
    min-height: 70vh;
}

.section {
    margin-bottom: 3rem;
    background-color: white;
    padding: 2rem;
    border-radius: 5px;
    box-shadow: var(--shadow);
}

.section-title {
    color: var(--primary-color);
    border-bottom: 2px solid var(--secondary-color);
    padding-bottom: 0.5rem;
}

/* 页脚 */
.footer {
    background-color: var(--primary-color);
    color: white;
    text-align: center;
    padding: 2rem 0;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-menu {
        flex-wrap: wrap;
    }
    
    .nav-item {
        margin: 0.5rem 1rem;
    }
}
/* 新增：自动高亮当前页面 */
.nav-link[href*="index.html"].current-page,
body[data-page="home"] .nav-link[href*="index.html"] {
    color: var(--primary-color);
    border-bottom: 2px solid var(--secondary-color);
}

/* 为每个页面添加类似规则 */
.nav-link[href*="research.html"].current-page,
body[data-page="research"] .nav-link[href*="research.html"] {
    color: var(--primary-color);
    border-bottom: 2px solid var(--secondary-color);
}

/* 语言切换器样式 */
.language-switcher {
    position: absolute;
    top: 20px;
    right: 20px;
}

.lang-btn {
    background: none;
    border: 1px solid #003366;
    color: #003366;
    padding: 3px 8px;
    margin-left: 5px;
    cursor: pointer;
    border-radius: 3px;
}

.lang-btn.active {
    background: #003366;
    color: white;
}
.container {
    max-width: 1100px;
    width: 100%;
    padding: 20px;
}

.slideshow {
    position: relative;
    overflow: hidden;
    border-radius: 8px;
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.5);
    aspect-ratio: 16/9;
}

.slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: opacity 1.2s ease-in-out;
    background-size: cover;
    background-position: center;
}

.slide.active {
    opacity: 1;
}

/* 导航按钮 */
.nav-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 20px;
    height: 20px;
    background: rgba(255, 255, 255, 0.2);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    backdrop-filter: blur(5px);
    z-index: 10;
}

.nav-btn:hover {
    background: rgba(255, 255, 255, 0.4);
    transform: translateY(-50%) scale(1.1);
}

.nav-btn i {
    color: white;
    font-size: 24px;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.prev-btn {
    left: 20px;
}

.next-btn {
    right: 20px;
}

/* 标题样式 */
.slide-title {
    position: absolute;
    bottom: 20px;
    left: 0;
    width: 100%;
    text-align: center;
    color: white;
    font-size: 1.5rem;
    padding: 10px;
    background: rgba(0, 0, 0, 0.4);
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.5s ease 0.2s;
}

.slide.active .slide-title {
    opacity: 1;
    transform: translateY(0);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-btn {
        width: 40px;
        height: 40px;
    }
    
    .nav-btn i {
        font-size: 18px;
    }
    
    .slide-title {
        font-size: 1.2rem;
        bottom: 10px;
    }
}