/* 基础重置和变量定义 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #FF6B6B;
    --secondary-color: #4ECDC4;
    --dark-bg: #1a1a2e;
    --darker-bg: #0f0f1e;
    --light-bg: #f8f9fa;
    --text-primary: #2d3436;
    --text-secondary: #636e72;
    --text-light: #ffffff;
    --border-color: #e0e0e0;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.15);
    --transition: all 0.3s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--light-bg);
    font-size: 16px;
}

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

/* 头部导航 */
.header {
    background: linear-gradient(135deg, var(--dark-bg) 0%, var(--darker-bg) 100%);
    color: var(--text-light);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

.logo h1 {
    font-size: 1.8rem;
    margin-bottom: 0.2rem;
    font-weight: 700;
}

.logo h1 a {
    color: var(--text-light);
    text-decoration: none;
}

.tagline {
    font-size: 0.9rem;
    color: var(--secondary-color);
    opacity: 0.9;
}

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

.nav-menu a {
    color: var(--text-light);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    padding: 0.5rem 0;
    position: relative;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--secondary-color);
}

.nav-menu a.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--secondary-color);
}

/* 主要内容区域 */
main {
    min-height: calc(100vh - 200px);
}

/* Hero区域 */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: var(--text-light);
    padding: 5rem 2rem;
    text-align: center;
}

.hero-content h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.hero-subtitle {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 0.95;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.hero-video {
    max-width: 800px;
    margin: 2rem auto;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
}

.hero-video video {
    width: 100%;
    height: auto;
    display: block;
    border-radius: 10px;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-top: 2rem;
}

/* 按钮样式 */
.btn {
    display: inline-block;
    padding: 0.8rem 2rem;
    text-decoration: none;
    border-radius: 5px;
    font-weight: 600;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: var(--text-light);
    color: var(--primary-color);
}

.btn-primary:hover {
    background: var(--light-bg);
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.btn-secondary {
    background: transparent;
    color: var(--text-light);
    border: 2px solid var(--text-light);
}

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

/* 特性区域 */
.features {
    padding: 4rem 0;
    background: var(--text-light);
}

.section-title {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 3rem;
    color: var(--text-primary);
    font-weight: 700;
}

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

.feature-card {
    background: var(--light-bg);
    padding: 2rem;
    border-radius: 10px;
    text-align: center;
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
    font-size: 1.3rem;
}

.feature-card h3 a {
    color: var(--text-primary);
    text-decoration: none;
    transition: var(--transition);
}

.feature-card h3 a:hover {
    color: var(--primary-color);
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.8;
}

/* 精选视频区域 */
.featured-videos {
    padding: 4rem 0;
    background: var(--text-light);
}

.videos-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.video-card {
    background: var(--light-bg);
    border-radius: 10px;
    overflow: hidden;
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.video-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.video-thumbnail {
    position: relative;
    width: 100%;
    padding-top: 56.25%; /* 16:9 比例 */
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    overflow: hidden;
}

.video-thumbnail img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    transition: var(--transition);
    display: block;
}

.video-thumbnail img:hover {
    transform: scale(1.05);
}

.video-thumbnail img[src=""],
.video-thumbnail img:not([src]) {
    opacity: 0;
}

/* 确保Bing图片正确加载 */
.video-thumbnail img {
    min-width: 100%;
    min-height: 100%;
}

.play-overlay {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 3rem;
    color: var(--text-light);
    opacity: 0.9;
    transition: var(--transition);
    z-index: 2;
}

.video-card:hover .play-overlay {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1.1);
}

.video-duration {
    position: absolute;
    bottom: 10px;
    right: 10px;
    background: rgba(0, 0, 0, 0.8);
    color: var(--text-light);
    padding: 0.3rem 0.6rem;
    border-radius: 4px;
    font-size: 0.85rem;
    z-index: 2;
}

.video-info {
    padding: 1.5rem;
}

.video-title {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.8rem;
    line-height: 1.4;
}

.video-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 1rem;
}

.video-meta {
    margin-bottom: 1rem;
}

.video-stats {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.video-stats span {
    display: inline-block;
}

.video-tags {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.video-tags .tag {
    display: inline-block;
    padding: 0.3rem 0.8rem;
    background: var(--primary-color);
    color: var(--text-light);
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 500;
}

/* 内容区域 */
.content-section {
    padding: 4rem 0;
    background: var(--light-bg);
}

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

.content-item {
    background: var(--text-light);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

.content-item h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.content-item p {
    color: var(--text-secondary);
    line-height: 1.8;
}

/* 页面头部 */
.page-header {
    background: linear-gradient(135deg, var(--dark-bg) 0%, var(--darker-bg) 100%);
    color: var(--text-light);
    padding: 3rem 0;
    text-align: center;
}

.page-header h1 {
    font-size: 2.2rem;
    margin-bottom: 1rem;
}

.breadcrumb {
    color: var(--secondary-color);
    font-size: 0.95rem;
}

.breadcrumb a {
    color: var(--secondary-color);
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

/* 主内容区域（内页） */
.main-content {
    background: var(--text-light);
    padding: 2.5rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.main-content h2 {
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    font-size: 1.8rem;
    border-bottom: 3px solid var(--primary-color);
    padding-bottom: 0.5rem;
}

.main-content h3 {
    color: var(--primary-color);
    margin-top: 2rem;
    margin-bottom: 1rem;
    font-size: 1.4rem;
}

.main-content p {
    color: var(--text-secondary);
    margin-bottom: 1.2rem;
    line-height: 1.8;
    text-align: justify;
}

/* 侧边栏 */
.sidebar {
    margin-bottom: 2rem;
}

.sidebar-widget {
    background: var(--text-light);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.sidebar-widget h3 {
    color: var(--text-primary);
    margin-bottom: 1rem;
    font-size: 1.3rem;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.sidebar-widget ul {
    list-style: none;
}

.sidebar-widget ul li {
    margin-bottom: 0.8rem;
}

.sidebar-widget ul li a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition);
    display: block;
    padding: 0.5rem;
    border-radius: 5px;
}

.sidebar-widget ul li a:hover {
    color: var(--primary-color);
    background: var(--light-bg);
    padding-left: 1rem;
}

.sidebar-widget p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 1rem;
    font-size: 0.95rem;
}

.sidebar-widget strong {
    color: var(--text-primary);
}

/* CTA区域 */
.cta-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: var(--text-light);
    padding: 4rem 2rem;
    text-align: center;
}

.cta-section h2 {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.cta-section p {
    font-size: 1.1rem;
    margin-bottom: 2rem;
    opacity: 0.95;
}

.cta-box {
    background: var(--light-bg);
    padding: 2rem;
    border-radius: 10px;
    margin-top: 2rem;
    text-align: center;
}

.cta-box h3 {
    color: var(--text-primary);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.cta-box p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.cta-box .btn {
    margin: 0 0.5rem;
}

/* 页脚 */
.footer {
    background: var(--dark-bg);
    color: var(--text-light);
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    margin-bottom: 1rem;
    color: var(--secondary-color);
    font-size: 1.2rem;
}

.footer-section p {
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.8;
    font-size: 0.95rem;
}

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

.footer-section ul li {
    margin-bottom: 0.8rem;
}

.footer-section ul li a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition);
}

.footer-section ul li a:hover {
    color: var(--secondary-color);
    padding-left: 0.5rem;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.9rem;
}

/* 响应式设计 - 平板 */
@media (max-width: 968px) {
    .nav-container {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-menu {
        gap: 1rem;
        justify-content: center;
    }

    .hero-content h2 {
        font-size: 2rem;
    }

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

    .content-section .container {
        display: block;
    }

    .main-content {
        margin-bottom: 2rem;
    }

    .sidebar {
        margin-bottom: 0;
    }
}

/* 响应式设计 - 移动端 */
@media (max-width: 768px) {
    body {
        font-size: 15px;
    }

    .container {
        padding: 0 15px;
    }

    .nav-container {
        padding: 0 15px;
    }

    .logo h1 {
        font-size: 1.5rem;
    }

    .tagline {
        font-size: 0.8rem;
    }

    .nav-menu {
        flex-direction: column;
        gap: 0.5rem;
        width: 100%;
        text-align: center;
    }

    .nav-menu li {
        width: 100%;
    }

    .nav-menu a {
        display: block;
        padding: 0.8rem;
        border-radius: 5px;
    }

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

    .hero {
        padding: 3rem 1.5rem;
    }

    .hero-content h2 {
        font-size: 1.8rem;
    }

    .hero-subtitle {
        font-size: 0.95rem;
    }

    .hero-video {
        margin: 1.5rem auto;
        max-width: 100%;
    }

    .hero-buttons {
        flex-direction: column;
        width: 100%;
    }

    .hero-buttons .btn {
        width: 100%;
    }

    .section-title {
        font-size: 1.6rem;
    }

    .features-grid,
    .content-grid,
    .videos-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .feature-card,
    .content-item {
        padding: 1.5rem;
    }

    .main-content {
        padding: 1.5rem;
    }

    .main-content h2 {
        font-size: 1.5rem;
    }

    .main-content h3 {
        font-size: 1.2rem;
    }

    .main-content p {
        font-size: 0.95rem;
        text-align: left;
    }

    .sidebar-widget {
        padding: 1.5rem;
    }

    .page-header {
        padding: 2rem 1rem;
    }

    .page-header h1 {
        font-size: 1.6rem;
    }

    .cta-section {
        padding: 3rem 1.5rem;
    }

    .cta-section h2 {
        font-size: 1.6rem;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .btn {
        padding: 0.7rem 1.5rem;
        font-size: 0.95rem;
    }

    .cta-box .btn {
        display: block;
        width: 100%;
        margin: 0.5rem 0;
    }
}

/* 响应式设计 - 小屏手机 */
@media (max-width: 480px) {
    body {
        font-size: 14px;
    }

    .hero-content h2 {
        font-size: 1.5rem;
    }

    .section-title {
        font-size: 1.4rem;
    }

    .page-header h1 {
        font-size: 1.4rem;
    }

    .main-content h2 {
        font-size: 1.3rem;
    }

    .main-content h3 {
        font-size: 1.1rem;
    }
}

/* 性能优化 - 减少重绘 */
.feature-card,
.content-item,
.sidebar-widget {
    will-change: transform;
}

/* 打印样式 */
@media print {
    .header,
    .footer,
    .nav-menu,
    .hero-buttons,
    .cta-section {
        display: none;
    }

    body {
        background: white;
        color: black;
    }
}