/* ============================================
   围棋在线教育平台 - 企业级主样式表
   东方水墨风 · 专业商务 · 禅意留白
   ============================================ */

/* CSS Reset & Base */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --color-ink: #1A1A1A;
    --color-paper: #F5F5F5;
    --color-gold: #D4AF37;
    --color-gold-light: #E8D48B;
    --color-gray-dark: #333333;
    --color-gray-mid: #666666;
    --color-gray-light: #999999;
    --color-border: #E0E0E0;
    --color-bg-section: #FAFAFA;
    --color-white: #FFFFFF;
    --font-heading: 'KaiTi', 'STKaiti', 'SimSun', serif;
    --font-body: 'Source Han Serif SC', 'Noto Serif SC', 'SimSun', 'STSong', serif;
    --font-sans: 'Microsoft YaHei', 'PingFang SC', 'Hiragino Sans GB', sans-serif;
    --max-width: 1200px;
    --header-height: 80px;
    --transition: all 0.3s ease;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    font-size: 1rem;
    line-height: 1.8;
    color: var(--color-ink);
    background-color: var(--color-paper);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-ink);
    text-decoration: none;
    transition: var(--transition);
}

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

ul, ol {
    list-style: none;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* ============================================
   Header & Navigation - 企业级导航
   ============================================ */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--header-height);
    background: rgba(245, 245, 245, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    transition: var(--transition);
}

.site-header.scrolled {
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
}

.header-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.site-logo {
    display: flex;
    align-items: center;
    gap: 12px;
}

.site-logo .logo-icon {
    width: 42px;
    height: 42px;
    border-radius: 50%;
    background: var(--color-ink);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.site-logo .logo-icon::before {
    content: '';
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--color-white);
    position: absolute;
    top: 10px;
    left: 10px;
}

.site-logo .logo-icon::after {
    content: '';
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--color-gold);
    position: absolute;
    bottom: 10px;
    right: 10px;
}

.site-logo .logo-text {
    font-family: var(--font-heading);
    font-size: 1.4rem;
    font-weight: bold;
    color: var(--color-ink);
    letter-spacing: 2px;
}

.main-nav {
    display: flex;
    align-items: center;
    gap: 32px;
}

.main-nav a {
    font-family: var(--font-sans);
    font-size: 0.95rem;
    color: var(--color-gray-dark);
    position: relative;
    padding: 8px 0;
}

.main-nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 2px;
    background: var(--color-gold);
    transition: var(--transition);
}

.main-nav a:hover::after,
.main-nav a.active::after {
    width: 100%;
}

.main-nav a:hover,
.main-nav a.active {
    color: var(--color-ink);
}

/* Mobile Menu Toggle */
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 10px;
}

.menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--color-ink);
    transition: var(--transition);
}

/* ============================================
   Hero Section - 首屏
   ============================================ */
.hero-section {
    position: relative;
    height: 100vh;
    min-height: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    margin-top: 0;
}

.hero-video-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 1;
}

.hero-image-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 1;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(
        to bottom,
        rgba(26, 26, 26, 0.4) 0%,
        rgba(26, 26, 26, 0.6) 50%,
        rgba(26, 26, 26, 0.8) 100%
    );
    z-index: 2;
}

.hero-content {
    position: relative;
    z-index: 3;
    text-align: center;
    color: var(--color-white);
    padding: 0 20px;
}

.hero-content h1 {
    font-family: var(--font-heading);
    font-size: 3.2rem;
    font-weight: normal;
    letter-spacing: 6px;
    margin-bottom: 20px;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

.hero-content .hero-subtitle {
    font-family: var(--font-body);
    font-size: 1.2rem;
    color: rgba(255, 255, 255, 0.85);
    margin-bottom: 40px;
    letter-spacing: 2px;
}

.hero-cta {
    display: flex;
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 14px 36px;
    font-family: var(--font-sans);
    font-size: 1rem;
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    letter-spacing: 1px;
}

.btn-primary {
    background: var(--color-gold);
    color: var(--color-ink);
    font-weight: bold;
}

.btn-primary:hover {
    background: var(--color-gold-light);
    color: var(--color-ink);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(212, 175, 55, 0.3);
}

.btn-outline {
    background: transparent;
    color: var(--color-white);
    border: 1px solid rgba(255, 255, 255, 0.6);
}

.btn-outline:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--color-white);
    color: var(--color-white);
    transform: translateY(-2px);
}

/* ============================================
   Section Styles - 通用模块
   ============================================ */
.section {
    padding: 80px 0;
}

.section-alt {
    background: var(--color-white);
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-header h2 {
    font-family: var(--font-heading);
    font-size: 2.2rem;
    color: var(--color-ink);
    margin-bottom: 16px;
    letter-spacing: 3px;
}

.section-header .section-line {
    width: 60px;
    height: 2px;
    background: var(--color-gold);
    margin: 0 auto 20px;
}

.section-header p {
    font-size: 1rem;
    color: var(--color-gray-mid);
    max-width: 600px;
    margin: 0 auto;
}

/* ============================================
   Course Cards - 课程体系
   ============================================ */
.course-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.course-card {
    background: var(--color-white);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.06);
    transition: var(--transition);
}

.course-card:hover {
    transform: translateY(-6px);
    box-shadow: 0 12px 32px rgba(0, 0, 0, 0.12);
}

.course-card .card-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.course-card .card-body {
    padding: 24px;
}

.course-card .card-tag {
    display: inline-block;
    padding: 4px 12px;
    background: rgba(212, 175, 55, 0.1);
    color: var(--color-gold);
    font-size: 0.8rem;
    border-radius: 20px;
    margin-bottom: 12px;
    font-family: var(--font-sans);
}

.course-card h3 {
    font-family: var(--font-heading);
    font-size: 1.3rem;
    margin-bottom: 10px;
    color: var(--color-ink);
}

.course-card p {
    font-size: 0.9rem;
    color: var(--color-gray-mid);
    margin-bottom: 16px;
}

.course-card .card-meta {
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
    color: var(--color-gray-light);
    font-family: var(--font-sans);
    border-top: 1px solid var(--color-border);
    padding-top: 12px;
}

/* ============================================
   AI Section - 左右分栏
   ============================================ */
.split-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.split-image {
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.1);
}

.split-image img {
    width: 100%;
    height: auto;
}

.split-content h2 {
    font-family: var(--font-heading);
    font-size: 2rem;
    margin-bottom: 20px;
    letter-spacing: 2px;
}

.split-content p {
    font-size: 1rem;
    color: var(--color-gray-mid);
    margin-bottom: 16px;
}

.feature-list {
    margin-top: 24px;
}

.feature-list li {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    margin-bottom: 16px;
    font-size: 0.95rem;
    color: var(--color-gray-dark);
    font-family: var(--font-sans);
}

.feature-list li::before {
    content: '●';
    color: var(--color-gold);
    font-size: 0.6rem;
    margin-top: 8px;
    flex-shrink: 0;
}

/* ============================================
   Teacher Cards - 名师团队
   ============================================ */
.teacher-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.teacher-card {
    text-align: center;
    background: var(--color-white);
    padding: 40px 24px;
    border-radius: 8px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.06);
    transition: var(--transition);
}

.teacher-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.1);
}

.teacher-card .teacher-avatar {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    object-fit: cover;
    margin: 0 auto 20px;
    border: 3px solid var(--color-border);
}

.teacher-card h3 {
    font-family: var(--font-heading);
    font-size: 1.3rem;
    margin-bottom: 8px;
}

.teacher-card .teacher-title {
    color: var(--color-gold);
    font-size: 0.9rem;
    margin-bottom: 12px;
    font-family: var(--font-sans);
}

.teacher-card p {
    font-size: 0.9rem;
    color: var(--color-gray-mid);
}

/* ============================================
   Stats Section - 数据展示
   ============================================ */
.stats-section {
    background: var(--color-ink);
    padding: 60px 0;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
    text-align: center;
}

.stat-item .stat-number {
    font-family: var(--font-sans);
    font-size: 2.8rem;
    font-weight: bold;
    color: var(--color-gold);
    margin-bottom: 8px;
}

.stat-item .stat-label {
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.7);
}

/* ============================================
   Page Banner - 内页横幅
   ============================================ */
.page-banner {
    position: relative;
    height: 360px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    margin-top: var(--header-height);
}

.page-banner img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.page-banner .banner-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(26, 26, 26, 0.6);
}

.page-banner .banner-content {
    position: relative;
    z-index: 2;
    text-align: center;
    color: var(--color-white);
}

.page-banner h1 {
    font-family: var(--font-heading);
    font-size: 2.6rem;
    letter-spacing: 4px;
    margin-bottom: 12px;
}

.page-banner .breadcrumb {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.7);
    font-family: var(--font-sans);
}

.page-banner .breadcrumb a {
    color: rgba(255, 255, 255, 0.7);
}

.page-banner .breadcrumb a:hover {
    color: var(--color-gold);
}

/* ============================================
   Content Pages - 内容页面
   ============================================ */
.content-section {
    padding: 60px 0;
}

.content-wrapper {
    max-width: 900px;
    margin: 0 auto;
}

.content-wrapper h2 {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    margin: 40px 0 20px;
    color: var(--color-ink);
    padding-left: 16px;
    border-left: 3px solid var(--color-gold);
}

.content-wrapper h3 {
    font-family: var(--font-heading);
    font-size: 1.4rem;
    margin: 30px 0 16px;
    color: var(--color-gray-dark);
}

.content-wrapper p {
    margin-bottom: 20px;
    color: var(--color-gray-dark);
    text-indent: 2em;
}

.content-wrapper ul, .content-wrapper ol {
    margin: 16px 0 24px 2em;
}

.content-wrapper li {
    margin-bottom: 10px;
    color: var(--color-gray-dark);
    list-style: disc;
}

/* Related Articles */
.related-articles {
    margin-top: 60px;
    padding-top: 40px;
    border-top: 1px solid var(--color-border);
}

.related-articles h3 {
    font-family: var(--font-heading);
    font-size: 1.4rem;
    margin-bottom: 20px;
    border-left: none;
    padding-left: 0;
}

.related-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
}

.related-list a {
    display: block;
    padding: 16px;
    background: var(--color-bg-section);
    border-radius: 6px;
    font-family: var(--font-sans);
    font-size: 0.95rem;
    color: var(--color-gray-dark);
    transition: var(--transition);
}

.related-list a:hover {
    background: rgba(212, 175, 55, 0.08);
    color: var(--color-gold);
}

/* ============================================
   Video Section
   ============================================ */
.video-container {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.1);
    margin: 30px 0;
}

.video-container video {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* ============================================
   Footer - 企业级页脚
   ============================================ */
.site-footer {
    background: var(--color-ink);
    color: rgba(255, 255, 255, 0.7);
    padding: 60px 0 0;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1.5fr;
    gap: 40px;
    padding-bottom: 40px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-col h4 {
    color: var(--color-white);
    font-family: var(--font-heading);
    font-size: 1.1rem;
    margin-bottom: 20px;
    letter-spacing: 1px;
}

.footer-col p {
    font-size: 0.9rem;
    line-height: 1.8;
    margin-bottom: 12px;
}

.footer-col .footer-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 16px;
}

.footer-col .footer-logo .logo-icon {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--color-gold);
    display: flex;
    align-items: center;
    justify-content: center;
}

.footer-col .footer-logo span {
    font-family: var(--font-heading);
    font-size: 1.2rem;
    color: var(--color-white);
}

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

.footer-links a {
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.9rem;
    font-family: var(--font-sans);
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--color-gold);
}

.footer-contact li {
    display: flex;
    align-items: flex-start;
    gap: 8px;
    margin-bottom: 14px;
    font-size: 0.9rem;
    font-family: var(--font-sans);
}

.footer-bottom {
    padding: 20px 0;
    text-align: center;
    font-size: 0.85rem;
    font-family: var(--font-sans);
}

.footer-bottom a {
    color: rgba(255, 255, 255, 0.5);
}

.footer-bottom a:hover {
    color: var(--color-gold);
}

/* ============================================
   Responsive Design - 响应式
   ============================================ */
@media (max-width: 1024px) {
    .course-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
    }
    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    :root {
        --header-height: 64px;
    }

    .main-nav {
        display: none;
        position: absolute;
        top: var(--header-height);
        left: 0;
        width: 100%;
        background: var(--color-paper);
        flex-direction: column;
        padding: 20px;
        gap: 0;
        border-bottom: 1px solid var(--color-border);
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    }

    .main-nav.active {
        display: flex;
    }

    .main-nav a {
        padding: 12px 0;
        border-bottom: 1px solid var(--color-border);
        width: 100%;
    }

    .menu-toggle {
        display: flex;
    }

    .hero-content h1 {
        font-size: 2rem;
        letter-spacing: 3px;
    }

    .hero-content .hero-subtitle {
        font-size: 1rem;
    }

    .section {
        padding: 50px 0;
    }

    .section-header h2 {
        font-size: 1.8rem;
    }

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

    .split-section {
        grid-template-columns: 1fr;
        gap: 30px;
    }

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

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

    .page-banner {
        height: 260px;
    }

    .page-banner h1 {
        font-size: 1.8rem;
    }

    .related-list {
        grid-template-columns: 1fr;
    }

    .hero-cta {
        flex-direction: column;
        align-items: center;
    }
}

@media (max-width: 480px) {
    .hero-content h1 {
        font-size: 1.6rem;
    }

    .stat-item .stat-number {
        font-size: 2rem;
    }
}

/* ============================================
   Animations - 动效
   ============================================ */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Ink wash transition effect */
.ink-reveal {
    opacity: 0;
    transition: opacity 0.8s ease;
}

.ink-reveal.visible {
    opacity: 1;
}

/* Button ripple effect */
.btn-ripple {
    position: relative;
    overflow: hidden;
}

.btn-ripple::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width 0.4s ease, height 0.4s ease;
}

.btn-ripple:hover::after {
    width: 200px;
    height: 200px;
}

/* Scroll indicator */
.scroll-indicator {
    position: absolute;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 3;
    animation: bounce 2s infinite;
}

.scroll-indicator span {
    display: block;
    width: 24px;
    height: 24px;
    border-right: 2px solid rgba(255, 255, 255, 0.6);
    border-bottom: 2px solid rgba(255, 255, 255, 0.6);
    transform: rotate(45deg);
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateX(-50%) translateY(0); }
    40% { transform: translateX(-50%) translateY(-10px); }
    60% { transform: translateX(-50%) translateY(-5px); }
}