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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #fff;
}

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

/* 导航栏 */
.navbar {
    background-color: #fff;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

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

.nav-brand {
    font-size: 1.5rem;
    font-weight: bold;
    color: #2c3e50;
}

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

.nav-menu a {
    text-decoration: none;
    color: #333;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-menu a:hover {
    color: #007bff;
}

/* Hero区域 */
.hero-section {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 4rem 0;
    text-align: center;
}

.hero-content h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

/* 产品区域 */
.product-section {
    padding: 4rem 0;
}

.product-section:nth-child(even) {
    background-color: #f8f9fa;
}

.product-header {
    text-align: center;
    margin-bottom: 3rem;
}

.product-header h2 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    color: #2c3e50;
}

.subtitle {
    font-size: 1.2rem;
    color: #666;
}

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

.feature-card {
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.2);
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #2c3e50;
}

.feature-card p {
    color: #666;
    line-height: 1.8;
}

/* 推荐视频板块 */
.recommended-videos-section {
    padding: 4rem 0;
    background-color: #fff;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-header h2 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    color: #2c3e50;
}

.section-subtitle {
    font-size: 1.1rem;
    color: #666;
}

.videos-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 2rem;
}

.video-card {
    background: white;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s, box-shadow 0.3s;
    cursor: pointer;
}

.video-card > a {
    display: block;
    text-decoration: none;
    color: inherit;
}

.video-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.2);
}

.video-thumbnail {
    position: relative;
    width: 100%;
    padding-top: 56.25%; /* 16:9 比例，aspect-ratio 的回退 */
    aspect-ratio: 16 / 9;
    background-color: #f0f0f0;
    overflow: hidden;
}

@supports (aspect-ratio: 16 / 9) {
    .video-thumbnail {
        padding-top: 0;
        height: auto;
    }
}

.video-thumbnail img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: block;
    object-fit: contain;
    object-position: center;
}

.recommended-videos-section .play-icon {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 60px;
    height: 60px;
    background-color: rgba(0, 0, 0, 0.7);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 24px;
    z-index: 2;
    transition: background-color 0.3s, transform 0.3s;
}

.recommended-videos-section .video-card:hover .play-icon {
    background-color: rgba(0, 123, 255, 0.9);
    transform: translate(-50%, -50%) scale(1.1);
}

.video-info {
    padding: 1.5rem;
}

.video-info h3 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: #2c3e50;
}

.video-info p {
    color: #666;
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

/* 常见问题 */
.faq-section {
    padding: 4rem 0;
    background-color: #f8f9fa;
}

.faq-section h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: #2c3e50;
}

.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    background: white;
    padding: 2rem;
    margin-bottom: 1.5rem;
    border-radius: 10px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.faq-item h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: #2c3e50;
}

.faq-item p {
    color: #666;
    line-height: 1.8;
}

/* 页脚 */
.footer {
    background-color: #2c3e50;
    color: white;
    padding: 3rem 0 1rem;
}

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

.footer-section h4 {
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

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

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: #bbb;
    text-decoration: none;
    transition: color 0.3s;
}

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

.newsletter-form {
    display: flex;
    gap: 0.5rem;
    margin-top: 1rem;
}

.newsletter-form input {
    flex: 1;
    padding: 0.75rem;
    border: none;
    border-radius: 4px;
    font-size: 0.9rem;
}

.newsletter-form button {
    padding: 0.75rem 1.5rem;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background-color 0.3s;
}

.newsletter-form button:hover {
    background-color: #0056b3;
}

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

.footer-bottom p {
    margin-bottom: 0.5rem;
    color: #bbb;
}

.footer-links {
    margin-top: 1rem;
}

.footer-links a {
    color: #bbb;
    text-decoration: none;
    margin: 0 1rem;
    transition: color 0.3s;
}

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

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

    .hero-content h1 {
        font-size: 2rem;
    }

    .product-header h2,
    .section-header h2,
    .faq-section h2 {
        font-size: 2rem;
    }

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

    .product-features {
        grid-template-columns: 1fr;
    }

    .newsletter-form {
        flex-direction: column;
    }
}


/* ============================================
   RECOMMENDED ARTICLES SECTION
   仅作用于 recommended-articles-section（推荐文章模块）
   ============================================ */
.recommended-articles-section {
    padding: 5rem 0;
    background: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
    position: relative;
    overflow: hidden;
}

.recommended-articles-section::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
        radial-gradient(900px 420px at 18% 20%, rgba(0, 123, 255, 0.10), transparent 60%),
        radial-gradient(900px 420px at 82% 35%, rgba(118, 75, 162, 0.09), transparent 60%);
    pointer-events: none;
}

.recommended-articles-section .container {
    position: relative;
    z-index: 1;
}

.recommended-articles-section .section-header {
    margin-bottom: 2.25rem;
}

.recommended-articles-section .articles-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.75rem;
    margin-top: 2.25rem;
}

.recommended-articles-section .article-card {
    border-radius: 16px;
    overflow: hidden;
    background: rgba(255, 255, 255, 0.95);
    border: 1px solid rgba(15, 23, 42, 0.08);
    box-shadow: 0 10px 28px rgba(15, 23, 42, 0.08);
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

.recommended-articles-section .article-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 18px 44px rgba(15, 23, 42, 0.14);
    border-color: rgba(0, 123, 255, 0.22);
}

.recommended-articles-section .article-card > a {
    display: flex;
    flex-direction: column;
    height: 100%;
    text-decoration: none;
    color: inherit;
}

.recommended-articles-section .article-thumbnail {
    position: relative;
    aspect-ratio: 16 / 9;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.18) 0%, rgba(118, 75, 162, 0.16) 100%);
    overflow: hidden;
}

.recommended-articles-section .article-thumbnail::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, rgba(0, 0, 0, 0.0) 40%, rgba(0, 0, 0, 0.22) 100%);
    opacity: 0.9;
    pointer-events: none;
}

.recommended-articles-section .article-thumbnail img {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease, filter 0.5s ease;
    filter: saturate(1.02) contrast(1.02);
}

.recommended-articles-section .article-card:hover .article-thumbnail img {
    transform: scale(1.06);
    filter: saturate(1.08) contrast(1.06);
}

.recommended-articles-section .article-badge {
    position: absolute;
    left: 16px;
    bottom: 14px;
    z-index: 2;
    width: 44px;
    height: 44px;
    border-radius: 999px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 16px;
    font-weight: 700;
    line-height: 1;
    background: rgba(255, 255, 255, 0.9);
    color: #0f172a;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.18);
    transform: translateY(0);
    transition: transform 0.25s ease, background 0.25s ease;
}

.recommended-articles-section .article-card:hover .article-badge {
    transform: translateY(-2px) scale(1.03);
    background: rgba(255, 255, 255, 0.98);
}

.recommended-articles-section .article-info {
    padding: 1.15rem 1.25rem 1.35rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.recommended-articles-section .article-info h3 {
    margin: 0;
    font-size: 1.05rem;
    font-weight: 700;
    color: #0f172a;
    line-height: 1.55;
    display: -webkit-box;
    line-clamp: 2;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.recommended-articles-section .article-info p {
    margin: 0;
    font-size: 0.92rem;
    color: #64748b;
    line-height: 1.7;
    display: -webkit-box;
    line-clamp: 3;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

@media (max-width: 1024px) {
    .recommended-articles-section .articles-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: 1.5rem;
    }
}

@media (max-width: 768px) {
    .recommended-articles-section {
        padding: 3.5rem 0;
    }
    .recommended-articles-section .articles-grid {
        grid-template-columns: 1fr;
        gap: 1.25rem;
    }
    .recommended-articles-section .article-badge {
        width: 42px;
        height: 42px;
        font-size: 16px;
        left: 14px;
        bottom: 12px;
    }
}