/* 全局变量定义 */
:root {
    --primary-color: #005eb8; /* 柳叶刀蓝 */
    --secondary-color: #003d7a;
    --accent-color: #e31837; /* 强调红 */
    --bg-color: #f8f9fa;
    --text-main: #333333;
    --text-light: #666666;
    --white: #ffffff;
    --border-color: #dee2e6;
    --font-serif: 'Georgia', 'Times New Roman', serif;
    --font-sans: 'Helvetica Neue', Arial, sans-serif;
}

/* 基础重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.6;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.3s;
}

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

ul {
    list-style: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 顶部学术栏 */
.academic-bar {
    background-color: var(--secondary-color);
    color: rgba(255,255,255,0.8);
    font-size: 0.8rem;
    padding: 8px 0;
}

.academic-flex {
    display: flex;
    justify-content: space-between;
}

.academic-links a {
    margin-left: 20px;
    color: rgba(255,255,255,0.8);
}

.academic-links a:hover {
    color: var(--white);
}

/* 主导航 */
.main-header {
    background-color: var(--white);
    border-bottom: 3px solid var(--primary-color);
    padding: 20px 0;
}

.header-grid {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    gap: 40px;
}

.journal-title {
    font-family: var(--font-serif);
    font-size: 2.2rem;
    color: var(--primary-color);
    font-weight: bold;
    letter-spacing: -1px;
}

.journal-sub {
    display: block;
    font-size: 0.8rem;
    color: var(--text-light);
    letter-spacing: 2px;
    text-transform: uppercase;
}

.primary-nav {
    display: flex;
    justify-content: center;
    gap: 25px;
}

.nav-item {
    font-weight: 600;
    color: var(--text-main);
    padding: 5px 0;
    position: relative;
}

.nav-item.active {
    color: var(--primary-color);
}

.nav-item.active::after {
    content: '';
    position: absolute;
    bottom: -28px;
    left: 0;
    width: 100%;
    height: 3px;
    background-color: var(--primary-color);
}

.search-box {
    display: flex;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    overflow: hidden;
}

.search-box input {
    border: none;
    padding: 8px 12px;
    outline: none;
    width: 180px;
    font-size: 0.9rem;
}

.btn-search {
    background-color: var(--primary-color);
    color: var(--white);
    border: none;
    padding: 0 15px;
    cursor: pointer;
    font-weight: bold;
    font-size: 0.85rem;
}

/* 主要布局 */
.main-layout {
    display: grid;
    grid-template-columns: 2.5fr 1fr;
    gap: 40px;
    margin-top: 40px;
    margin-bottom: 60px;
}

/* 左侧内容 */
.article-meta {
    display: flex;
    gap: 15px;
    font-size: 0.85rem;
    color: var(--text-light);
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.article-type {
    color: var(--accent-color);
    font-weight: bold;
}

.featured-article {
    background-color: var(--white);
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    margin-bottom: 30px;
    border-left: 5px solid var(--primary-color);
}

.article-title {
    font-family: var(--font-serif);
    font-size: 1.8rem;
    margin-bottom: 10px;
    line-height: 1.3;
}

.article-title a:hover {
    color: var(--primary-color);
}

.article-authors {
    font-style: italic;
    color: var(--text-light);
    margin-bottom: 20px;
    font-size: 0.95rem;
}

.article-abstract p {
    margin-bottom: 10px;
    text-align: justify;
}

.read-more {
    display: inline-block;
    margin-top: 10px;
    color: var(--primary-color);
    font-weight: bold;
    font-size: 0.9rem;
}

/* 文章网格 */
.articles-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

.article-card {
    background-color: var(--white);
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
    transition: transform 0.3s, box-shadow 0.3s;
    position: relative;
    overflow: hidden;
}

.article-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.card-tag {
    display: inline-block;
    padding: 3px 8px;
    font-size: 0.7rem;
    font-weight: bold;
    color: var(--white);
    margin-bottom: 10px;
    text-transform: uppercase;
    border-radius: 2px;
}

.card-tag.clinical { background-color: #28a745; }
.card-tag.policy { background-color: #fd7e14; }
.card-tag.tech { background-color: #17a2b8; }
.card-tag.mental { background-color: #6f42c1; }

.article-card h3 {
    font-family: var(--font-serif);
    font-size: 1.1rem;
    margin-bottom: 10px;
    line-height: 1.4;
}

.card-summary {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-bottom: 15px;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.card-footer {
    display: flex;
    justify-content: space-between;
    font-size: 0.8rem;
    color: #999;
    border-top: 1px solid #eee;
    padding-top: 10px;
}

/* 右侧侧边栏 */
.widget {
    background-color: var(--white);
    padding: 25px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
    margin-bottom: 20px;
}

.widget-title {
    font-size: 1.1rem;
    color: var(--primary-color);
    border-bottom: 2px solid #eee;
    padding-bottom: 10px;
    margin-bottom: 20px;
    font-weight: bold;
}

/* 影响因子 */
.metric-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.metric-label {
    font-size: 0.9rem;
    color: var(--text-light);
}

.metric-value {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--secondary-color);
}

.metric-note {
    font-size: 0.75rem;
    color: #999;
    text-align: right;
}

/* 热门下载 */
.popular-list li {
    padding: 12px 0;
    border-bottom: 1px solid #f0f0f0;
    display: flex;
    gap: 10px;
    align-items: baseline;
}

.popular-list li:last-child {
    border-bottom: none;
}

.rank {
    font-weight: bold;
    color: var(--primary-color);
    min-width: 20px;
}

.popular-list a {
    font-size: 0.9rem;
    line-height: 1.4;
}

/* 订阅表单 */
.newsletter-widget p {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-bottom: 15px;
}

.sub-form {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.sub-form input {
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.sub-form button {
    padding: 10px;
    background-color: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-weight: bold;
    transition: background-color 0.3s;
}

.sub-form button:hover {
    background-color: var(--secondary-color);
}

/* 页脚 */
.site-footer {
    background-color: #2c3e50;
    color: #ecf0f1;
    padding: 50px 0 20px;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
    margin-bottom: 40px;
}

.footer-col h4 {
    color: var(--white);
    margin-bottom: 20px;
    font-size: 1.1rem;
    border-bottom: 1px solid #34495e;
    padding-bottom: 10px;
    display: inline-block;
}

.footer-col ul li {
    margin-bottom: 10px;
}

.footer-col ul li a {
    color: #bdc3c7;
    font-size: 0.9rem;
}

.footer-col ul li a:hover {
    color: var(--white);
}

.copyright-line {
    text-align: center;
    border-top: 1px solid #34495e;
    padding-top: 20px;
    font-size: 0.8rem;
    color: #95a5a6;
}

/* 响应式适配 */
@media (max-width: 900px) {
    .main-layout {
        grid-template-columns: 1fr;
    }
    
    .header-grid {
        grid-template-columns: 1fr;
        gap: 20px;
        text-align: center;
    }
    
    .primary-nav {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .nav-item.active::after {
        display: none;
    }
    
    .articles-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }
}