/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2E86AB;
    --secondary-color: #A23B72;
    --accent-color: #F18F01;
    --text-dark: #2C3E50;
    --text-light: #7F8C8D;
    --bg-light: #F8F9FA;
    --bg-white: #FFFFFF;
    --border-color: #E0E0E0;
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--text-dark);
    line-height: 1.6;
    background-color: var(--bg-light);
}

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

/* 导航栏 */
.navbar {
    background-color: var(--bg-white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 20px;
}

.logo h1 {
    font-size: 1.5rem;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary-color);
}

/* Hero区域 */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: 4rem 0;
    text-align: center;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.hero .subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 3rem;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.stat-card {
    background-color: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: 2rem;
    border-radius: 10px;
    transition: transform 0.3s;
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: bold;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1rem;
    opacity: 0.9;
}

/* Features区域 */
.features, .highlights {
    padding: 4rem 0;
}

.features h2, .highlights h2 {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 3rem;
    color: var(--text-dark);
}

.feature-grid, .highlight-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-card, .highlight-item {
    background-color: var(--bg-white);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
    transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(0,0,0,0.15);
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.feature-card p {
    color: var(--text-light);
    margin-bottom: 1.5rem;
}

.highlight-item h4 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: var(--secondary-color);
}

.highlight-item p {
    color: var(--text-light);
}

/* 按钮 */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    background-color: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 5px;
    transition: background-color 0.3s;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn:hover {
    background-color: var(--secondary-color);
}

.btn-secondary {
    background-color: var(--accent-color);
}

.btn-secondary:hover {
    background-color: #D67A00;
}

/* 页脚 */
footer {
    background-color: var(--text-dark);
    color: white;
    text-align: center;
    padding: 2rem 0;
    margin-top: 4rem;
}

/* 筛选器和搜索 */
.filters {
    background-color: var(--bg-white);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.filter-group {
    margin-bottom: 1.5rem;
}

.filter-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.filter-group input,
.filter-group select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    font-size: 1rem;
}

.filter-group input:focus,
.filter-group select:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* 论文列表 */
.paper-list {
    display: grid;
    gap: 1.5rem;
}

.paper-card {
    background-color: var(--bg-white);
    padding: 1.5rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
    transition: transform 0.3s;
}

.paper-card:hover {
    transform: translateX(5px);
}

.paper-card h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.paper-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-top: 1rem;
    font-size: 0.9rem;
    color: var(--text-light);
}

.paper-meta span {
    padding: 0.25rem 0.75rem;
    background-color: var(--bg-light);
    border-radius: 3px;
}

/* 图表容器 */
.chart-container {
    background-color: var(--bg-white);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.chart-container h3 {
    margin-bottom: 1.5rem;
    color: var(--text-dark);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .navbar .container {
        flex-direction: column;
        gap: 1rem;
    }

    .hero h1 {
        font-size: 1.8rem;
    }

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

    .feature-grid, .highlight-grid {
        grid-template-columns: 1fr;
    }
}