/* ==================== 数学学科样式表 ==================== */
/* 主题色：蓝色系，学术风格 */

:root {
    --primary-color: #1e5aa8;
    --primary-dark: #153d75;
    --primary-light: #4a90d9;
    --secondary-color: #2c3e50;
    --accent-color: #3498db;
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-light: #666666;
    --border-color: #e0e0e0;
    --sidebar-bg: #f0f4f8;
    --hover-bg: #e8f1f8;
    --success-color: #27ae60;
    --warning-color: #f39c12;
}

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

body {
    font-family: "Microsoft YaHei", "PingFang SC", "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* ==================== 导航栏 ==================== */
.navbar {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    padding: 0 20px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
}

.logo {
    display: flex;
    align-items: center;
    color: white;
    text-decoration: none;
    font-size: 1.4rem;
    font-weight: bold;
}

.logo-icon {
    font-size: 1.8rem;
    margin-right: 10px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-links a {
    color: rgba(255,255,255,0.9);
    text-decoration: none;
    font-size: 0.95rem;
    transition: color 0.3s;
    padding: 5px 10px;
    border-radius: 4px;
}

.nav-links a:hover {
    color: white;
    background-color: rgba(255,255,255,0.1);
}

.back-home {
    color: white;
    text-decoration: none;
    padding: 8px 16px;
    border: 1px solid rgba(255,255,255,0.5);
    border-radius: 20px;
    font-size: 0.9rem;
    transition: all 0.3s;
}

.back-home:hover {
    background-color: white;
    color: var(--primary-color);
}

/* ==================== 页面头部 ==================== */
.page-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    color: white;
    padding: 60px 20px;
    text-align: center;
}

.page-header h1 {
    font-size: 2.5rem;
    margin-bottom: 15px;
    font-weight: 300;
}

.page-header p {
    font-size: 1.1rem;
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto;
}

/* ==================== 主容器 ==================== */
.main-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 40px 20px;
}

/* ==================== 知识模块卡片 ==================== */
.section-title {
    font-size: 1.8rem;
    color: var(--secondary-color);
    margin-bottom: 30px;
    padding-bottom: 10px;
    border-bottom: 3px solid var(--primary-color);
    display: inline-block;
}

.modules-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
    margin-bottom: 50px;
}

.module-card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 30px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.08);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
    text-decoration: none;
    color: var(--text-color);
    display: block;
}

.module-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(30, 90, 168, 0.15);
    border-color: var(--primary-light);
}

.module-icon {
    font-size: 3rem;
    margin-bottom: 15px;
}

.module-card h3 {
    font-size: 1.3rem;
    color: var(--primary-color);
    margin-bottom: 10px;
}

.module-card p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.6;
}

.module-topics {
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px dashed var(--border-color);
    font-size: 0.85rem;
    color: var(--text-light);
}

/* ==================== 学习路径 ==================== */
.path-section {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 40px;
    margin-bottom: 40px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.08);
}

.path-timeline {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-top: 30px;
    position: relative;
}

.path-timeline::before {
    content: '';
    position: absolute;
    top: 25px;
    left: 10%;
    right: 10%;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
}

.path-item {
    text-align: center;
    flex: 1;
    position: relative;
    z-index: 1;
}

.path-number {
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: bold;
    margin: 0 auto 15px;
    border: 4px solid var(--card-bg);
}

.path-item h4 {
    color: var(--secondary-color);
    margin-bottom: 8px;
}

.path-item p {
    font-size: 0.85rem;
    color: var(--text-light);
    padding: 0 10px;
}

/* ==================== 侧边栏布局 ==================== */
.content-wrapper {
    display: flex;
    gap: 30px;
    max-width: 1400px;
    margin: 0 auto;
    padding: 30px 20px;
}

.sidebar {
    width: 280px;
    flex-shrink: 0;
    background: var(--sidebar-bg);
    border-radius: 12px;
    padding: 25px;
    height: fit-content;
    position: sticky;
    top: 80px;
}

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

.sidebar-nav {
    list-style: none;
}

.sidebar-nav li {
    margin-bottom: 8px;
}

.sidebar-nav a {
    display: block;
    padding: 10px 15px;
    color: var(--text-color);
    text-decoration: none;
    border-radius: 6px;
    transition: all 0.3s;
    font-size: 0.95rem;
}

.sidebar-nav a:hover {
    background-color: var(--hover-bg);
    color: var(--primary-color);
}

.sidebar-nav a.active {
    background-color: var(--primary-color);
    color: white;
}

.content-area {
    flex: 1;
    background: var(--card-bg);
    border-radius: 12px;
    padding: 40px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.08);
    min-height: 600px;
}

.content-area h2 {
    color: var(--primary-color);
    font-size: 1.8rem;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border-color);
}

.content-area h3 {
    color: var(--secondary-color);
    font-size: 1.3rem;
    margin: 30px 0 15px;
}

.content-area p {
    margin-bottom: 15px;
    line-height: 1.8;
    color: var(--text-color);
}

.placeholder-text {
    color: var(--text-light);
    font-style: italic;
    padding: 40px;
    text-align: center;
    background: var(--bg-color);
    border-radius: 8px;
    border: 2px dashed var(--border-color);
}

/* ==================== 页脚 ==================== */
.footer {
    background-color: var(--secondary-color);
    color: rgba(255,255,255,0.8);
    padding: 30px 20px;
    text-align: center;
    margin-top: 50px;
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
}

.footer-links {
    margin-bottom: 15px;
}

.footer-links a {
    color: rgba(255,255,255,0.8);
    text-decoration: none;
    margin: 0 15px;
    font-size: 0.9rem;
}

.footer-links a:hover {
    color: white;
}

.icp {
    font-size: 0.85rem;
    color: rgba(255,255,255,0.6);
}

/* ==================== 响应式设计 ==================== */
@media (max-width: 968px) {
    .content-wrapper {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        position: static;
    }
    
    .path-timeline {
        flex-direction: column;
        gap: 30px;
    }
    
    .path-timeline::before {
        display: none;
    }
    
    .nav-links {
        display: none;
    }
    
    .page-header h1 {
        font-size: 1.8rem;
    }
}

@media (max-width: 600px) {
    .modules-grid {
        grid-template-columns: 1fr;
    }
    
    .main-container {
        padding: 20px 15px;
    }
    
    .path-section {
        padding: 25px;
    }
}