/* 基础样式重置和变量定义 - Notion风格 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Notion风格色彩 */
    --primary-blue: #2563eb;
    --primary-orange: #ea580c;
    --primary-gray: #6b7280;
    --accent-blue: #3b82f6;
    --accent-orange: #f97316;
    
    /* Notion风格灰度色彩 */
    --gray-50: #fafafa;
    --gray-100: #f5f5f5;
    --gray-200: #e5e5e5;
    --gray-300: #d4d4d4;
    --gray-400: #a3a3a3;
    --gray-500: #737373;
    --gray-600: #525252;
    --gray-700: #404040;
    --gray-800: #262626;
    --gray-900: #171717;
    
    /* 语义色彩 */
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --info: #3b82f6;
    
    /* 字体 */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    
    /* Notion风格阴影 */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.03);
    --shadow-md: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px 0 rgb(0 0 0 / 0.06);
    --shadow-lg: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -1px rgb(0 0 0 / 0.06);
    --shadow-xl: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -2px rgb(0 0 0 / 0.05);
    
    /* 圆角 */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* 间距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
}

/* Notion风格基础样式 */
body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--gray-800);
    background-color: white;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* Notion风格导航栏 */
.navbar {
    background: white;
    color: var(--gray-800);
    padding: var(--spacing-md) 0;
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid var(--gray-200);
    backdrop-filter: blur(8px);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 1.25rem;
    font-weight: 600;
}

.nav-brand i {
    width: 24px;
    height: 24px;
}

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--gray-600);
    text-decoration: none;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    transition: all 0.2s ease;
}

.nav-link:hover {
    background-color: var(--gray-100);
    color: var(--gray-800);
}

.nav-link i {
    width: 18px;
    height: 18px;
}

/* 主要内容区域 */
.main-content {
    min-height: calc(100vh - 80px);
}

/* Notion风格英雄区域 */
.hero-section {
    background: white;
    color: var(--gray-800);
    padding: var(--spacing-3xl) 0;
    text-align: center;
    border-bottom: 1px solid var(--gray-200);
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
}

.hero-title i {
    width: 48px;
    height: 48px;
}

.hero-description {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-2xl);
    opacity: 0.9;
    line-height: 1.7;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-2xl);
    margin-top: var(--spacing-2xl);
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-blue);
}

.stat-label {
    font-size: 0.875rem;
    opacity: 0.8;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Notion风格学习路径时间线 */
.learning-path {
    padding: var(--spacing-3xl) 0;
    background: white;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 600;
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    color: var(--gray-800);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
}

.section-title i {
    width: 32px;
    height: 32px;
    color: var(--primary-blue);
}

.path-timeline {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
}

.path-timeline::before {
    content: '';
    position: absolute;
    left: 50%;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--gray-300);
    transform: translateX(-50%);
}

.timeline-item {
    display: flex;
    align-items: center;
    margin-bottom: var(--spacing-2xl);
    position: relative;
}

.timeline-item:nth-child(odd) {
    flex-direction: row;
}

.timeline-item:nth-child(even) {
    flex-direction: row-reverse;
}

.timeline-marker {
    width: 48px;
    height: 48px;
    background: var(--primary-blue);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 1.125rem;
    position: relative;
    z-index: 2;
    border: 3px solid white;
    box-shadow: var(--shadow-md);
}

.timeline-content {
    flex: 1;
    background: white;
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    margin: 0 var(--spacing-lg);
    border: 1px solid var(--gray-200);
    transition: all 0.3s ease;
}

.timeline-content:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.timeline-content h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-blue);
    margin-bottom: var(--spacing-xs);
}

.timeline-content p {
    color: var(--gray-600);
    font-size: 0.875rem;
}

/* Notion风格模块网格 */
.modules-section {
    padding: var(--spacing-3xl) 0;
    background: white;
    border-top: 1px solid var(--gray-200);
}

.modules-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-2xl);
}

.module-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--gray-200);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.module-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-blue);
}

.module-card:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--gray-300);
}

.module-icon {
    width: 64px;
    height: 64px;
    background: var(--gray-100);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
    color: var(--primary-blue);
    border: 1px solid var(--gray-200);
}

.module-icon i {
    width: 32px;
    height: 32px;
}

.module-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: var(--spacing-md);
}

.module-description {
    color: var(--gray-600);
    line-height: 1.6;
    margin-bottom: var(--spacing-lg);
}

.module-features {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-lg);
}

.feature-tag {
    background: var(--gray-100);
    color: var(--gray-700);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.module-button {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    background: var(--primary-blue);
    color: white;
    text-decoration: none;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-weight: 500;
    transition: all 0.2s ease;
    border: none;
}

.module-button:hover {
    background: var(--accent-blue);
    box-shadow: var(--shadow-md);
}

.module-button i {
    width: 16px;
    height: 16px;
}

/* Notion风格快速开始区域 */
.quick-start {
    background: var(--gray-50);
    color: var(--gray-800);
    padding: var(--spacing-3xl) 0;
    text-align: center;
    border-top: 1px solid var(--gray-200);
}

.quick-start-title {
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
}

.quick-start-title i {
    width: 32px;
    height: 32px;
}

.quick-start-description {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-2xl);
    opacity: 0.9;
}

.quick-start-options {
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

.quick-option {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: var(--radius-lg);
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    min-width: 200px;
    justify-content: center;
}

.quick-option.primary {
    background: var(--primary-blue);
    color: white;
    border: 1px solid var(--primary-blue);
}

.quick-option.secondary {
    background: white;
    color: var(--primary-blue);
    border: 1px solid var(--primary-blue);
}

.quick-option:hover {
    box-shadow: var(--shadow-md);
}

.quick-option.primary:hover {
    background: var(--accent-blue);
}

.quick-option.secondary:hover {
    background: var(--gray-50);
}

.quick-option i {
    width: 20px;
    height: 20px;
}

/* 页脚 */
.footer {
    background: var(--gray-800);
    color: var(--gray-300);
    padding: var(--spacing-2xl) 0;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
}

.footer-section h3 {
    color: white;
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.footer-section ul {
    list-style: none;
}

.footer-section li {
    margin-bottom: var(--spacing-xs);
}

.footer-section a {
    color: var(--gray-300);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section a:hover {
    color: var(--primary-orange);
}

.footer-section p {
    color: var(--gray-400);
    font-size: 0.875rem;
    line-height: 1.6;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .nav-container {
        padding: 0 var(--spacing-md);
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .hero-title {
        font-size: 2rem;
        flex-direction: column;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: var(--spacing-lg);
    }
    
    .section-title {
        font-size: 2rem;
        flex-direction: column;
    }
    
    .path-timeline::before {
        left: 24px;
    }
    
    .timeline-item {
        flex-direction: row !important;
        padding-left: 60px;
    }
    
    .timeline-marker {
        position: absolute;
        left: 0;
    }
    
    .timeline-content {
        margin-left: 0;
    }
    
    .modules-grid {
        grid-template-columns: 1fr;
    }
    
    .quick-start-options {
        flex-direction: column;
        align-items: center;
    }
    
    .quick-option {
        width: 100%;
        max-width: 300px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.75rem;
    }
    
    .hero-description {
        font-size: 1rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .module-card {
        padding: var(--spacing-lg);
    }
    
    .quick-start-title {
        font-size: 2rem;
    }
}

/* 动画效果 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

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

.hero-content {
    animation: fadeInUp 0.8s ease-out;
}

.timeline-item:nth-child(odd) .timeline-content {
    animation: fadeInLeft 0.6s ease-out;
}

.timeline-item:nth-child(even) .timeline-content {
    animation: fadeInRight 0.6s ease-out;
}

.module-card {
    animation: fadeInUp 0.6s ease-out;
}

/* 加载状态 */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid var(--gray-300);
    border-top: 2px solid var(--primary-blue);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}