/* 全局样式 */
:root {
    --primary-color: #3b82f6;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    --text-color: #333;
    --text-light: #666;
    --background-color: #f9fafb;
    --white: #ffffff;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --border-radius: 8px;
    --box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 按钮样式 */
.btn {
    display: inline-block;
    padding: 10px 20px;
    border-radius: var(--border-radius);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    font-size: 16px;
}

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

.btn-primary:hover {
    background-color: #2563eb;
    transform: translateY(-2px);
}

.btn-outline {
    background-color: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-outline:hover {
    background-color: var(--primary-color);
    color: var(--white);
}

/* 导航栏样式 */
.navbar {
    background-color: var(--white);
    box-shadow: var(--box-shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.logo a {
    font-size: 24px;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 30px;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: var(--transition);
}

.nav-links a:hover {
    color: var(--primary-color);
}

.auth-buttons {
    display: flex;
    gap: 10px;
}

.mobile-menu {
    display: none;
    font-size: 24px;
    cursor: pointer;
}

/* 英雄区域样式 */
.hero {
    background-color: var(--white);
    padding: 80px 0;
}

.hero .container {
    display: flex;
    align-items: center;
    gap: 40px;
}

.hero-content {
    flex: 1;
}

.hero-content h1 {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 20px;
    line-height: 1.2;
}

.hero-content p {
    font-size: 18px;
    color: var(--text-light);
    margin-bottom: 30px;
}

.hero-buttons {
    display: flex;
    gap: 15px;
    margin-bottom: 40px;
}

.hero-stats {
    display: flex;
    gap: 30px;
}

.stat-item {
    display: flex;
    flex-direction: column;
}

.stat-number {
    font-size: 24px;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    font-size: 14px;
    color: var(--text-light);
}

.hero-image {
    flex: 1;
}

.hero-image img {
    width: 100%;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

/* 课程分类样式 */
.categories {
    padding: 80px 0;
    background-color: var(--background-color);
}

.categories h2 {
    font-size: 36px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 10px;
}

.categories p {
    text-align: center;
    color: var(--text-light);
    margin-bottom: 40px;
    font-size: 18px;
}

.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}

.category-card {
    background-color: var(--white);
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    text-align: center;
    transition: var(--transition);
}

.category-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

.category-icon {
    width: 60px;
    height: 60px;
    background-color: rgba(59, 130, 246, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 24px;
    color: var(--primary-color);
}

.category-card h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 10px;
}

.category-card p {
    font-size: 14px;
    color: var(--text-light);
    margin: 0;
}

/* 热门课程样式 */
.popular-courses {
    padding: 80px 0;
    background-color: var(--white);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
}

.section-header h2 {
    font-size: 36px;
    font-weight: 700;
}

.view-all {
    text-decoration: none;
    color: var(--primary-color);
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 5px;
    transition: var(--transition);
}

.view-all:hover {
    color: #2563eb;
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.course-card {
    background-color: var(--white);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    overflow: hidden;
    transition: var(--transition);
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

.course-image {
    position: relative;
    overflow: hidden;
}

.course-image img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    transition: var(--transition);
}

.course-card:hover .course-image img {
    transform: scale(1.05);
}

.course-badge {
    position: absolute;
    top: 10px;
    right: 10px;
    background-color: var(--accent-color);
    color: var(--white);
    padding: 5px 10px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: 600;
}

.course-content {
    padding: 20px;
}

.course-category {
    font-size: 12px;
    color: var(--primary-color);
    font-weight: 600;
    text-transform: uppercase;
    margin-bottom: 10px;
}

.course-content h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 10px;
}

.course-content p {
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 20px;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.course-rating {
    display: flex;
    align-items: center;
    gap: 5px;
}

.course-rating i {
    color: var(--accent-color);
    font-size: 14px;
}

.course-rating span {
    font-size: 14px;
    font-weight: 600;
}

.course-price {
    font-size: 18px;
    font-weight: 700;
    color: var(--primary-color);
}

/* 学习路径样式 */
.learning-paths {
    padding: 80px 0;
    background-color: var(--background-color);
}

.learning-paths h2 {
    font-size: 36px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 10px;
}

.learning-paths p {
    text-align: center;
    color: var(--text-light);
    margin-bottom: 40px;
    font-size: 18px;
}

.paths-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}

.path-card {
    background-color: var(--white);
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    text-align: center;
    transition: var(--transition);
}

.path-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

.path-icon {
    width: 80px;
    height: 80px;
    background-color: rgba(59, 130, 246, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 32px;
    color: var(--primary-color);
}

.path-card h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 15px;
}

.path-card p {
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 20px;
}

.path-details {
    display: flex;
    justify-content: space-between;
    margin-bottom: 20px;
    padding: 10px 0;
    border-top: 1px solid var(--gray-200);
    border-bottom: 1px solid var(--gray-200);
}

.path-courses, .path-duration {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-color);
}

/* 教师团队样式 */
.instructors {
    padding: 80px 0;
    background-color: var(--white);
}

.instructors-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.instructor-card {
    background-color: var(--white);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    overflow: hidden;
    text-align: center;
    transition: var(--transition);
}

.instructor-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

.instructor-image img {
    width: 100%;
    height: 250px;
    object-fit: cover;
}

.instructor-card h3 {
    font-size: 18px;
    font-weight: 600;
    margin: 20px 0 5px;
}

.instructor-card p {
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 15px;
}

.instructor-courses {
    font-size: 14px;
    font-weight: 600;
    color: var(--primary-color);
    padding: 0 20px 20px;
}

/* 学生评价样式 */
.testimonials {
    padding: 80px 0;
    background-color: var(--background-color);
}

.testimonials h2 {
    font-size: 36px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 10px;
}

.testimonials p {
    text-align: center;
    color: var(--text-light);
    margin-bottom: 40px;
    font-size: 18px;
}

.testimonials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.testimonial-card {
    background-color: var(--white);
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    transition: var(--transition);
}

.testimonial-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

.testimonial-rating {
    margin-bottom: 20px;
}

.testimonial-rating i {
    color: var(--accent-color);
    font-size: 16px;
}

.testimonial-card p {
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 20px;
    text-align: left;
    font-style: italic;
}

.testimonial-author {
    display: flex;
    align-items: center;
    gap: 15px;
}

.testimonial-author img {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    object-fit: cover;
}

.testimonial-author h4 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 2px;
}

.testimonial-author p {
    font-size: 14px;
    color: var(--text-light);
    margin: 0;
}

/* 常见问题样式 */
.faq {
    padding: 80px 0;
    background-color: var(--white);
}

.faq h2 {
    font-size: 36px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 40px;
}

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

.faq-item {
    margin-bottom: 15px;
    border: 1px solid var(--gray-200);
    border-radius: var(--border-radius);
    overflow: hidden;
}

.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px;
    background-color: var(--gray-100);
    cursor: pointer;
    transition: var(--transition);
}

.faq-question:hover {
    background-color: var(--gray-200);
}

.faq-question h3 {
    font-size: 16px;
    font-weight: 600;
    margin: 0;
}

.faq-question i {
    font-size: 14px;
    transition: var(--transition);
}

.faq-answer {
    padding: 0 20px;
    max-height: 0;
    overflow: hidden;
    transition: var(--transition);
}

.faq-answer p {
    margin: 0;
    padding: 20px 0;
    color: var(--text-light);
}

.faq-item.active .faq-answer {
    max-height: 200px;
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
}

/* 订阅区域样式 */
.subscribe {
    padding: 80px 0;
    background-color: var(--primary-color);
    color: var(--white);
    text-align: center;
}

.subscribe h2 {
    font-size: 36px;
    font-weight: 700;
    margin-bottom: 10px;
}

.subscribe p {
    font-size: 18px;
    margin-bottom: 30px;
    opacity: 0.9;
}

.subscribe-form {
    display: flex;
    max-width: 600px;
    margin: 0 auto;
    gap: 10px;
}

.subscribe-form input {
    flex: 1;
    padding: 15px 20px;
    border: none;
    border-radius: var(--border-radius);
    font-size: 16px;
}

.subscribe-form button {
    padding: 15px 30px;
}

/* 页脚样式 */
.footer {
    background-color: var(--gray-900);
    color: var(--white);
    padding: 60px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-logo h3 {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 15px;
}

.footer-logo p {
    font-size: 14px;
    color: var(--gray-400);
    margin-bottom: 20px;
}

.social-links {
    display: flex;
    gap: 15px;
}

.social-links a {
    width: 40px;
    height: 40px;
    background-color: var(--gray-800);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    transition: var(--transition);
}

.social-links a:hover {
    background-color: var(--primary-color);
    transform: translateY(-3px);
}

.footer-links h4 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 20px;
}

.footer-links a {
    display: block;
    color: var(--gray-400);
    text-decoration: none;
    margin-bottom: 10px;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--white);
    transform: translateX(5px);
}

.footer-bottom {
    border-top: 1px solid var(--gray-800);
    padding-top: 30px;
    text-align: center;
    font-size: 14px;
    color: var(--gray-400);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .navbar .nav-links, .navbar .auth-buttons {
        display: none;
    }
    
    .mobile-menu {
        display: block;
    }
    
    .hero .container {
        flex-direction: column;
        text-align: center;
    }
    
    .hero-content h1 {
        font-size: 36px;
    }
    
    .hero-buttons {
        justify-content: center;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .section-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    
    .subscribe-form {
        flex-direction: column;
    }
    
    .categories-grid, .courses-grid, .paths-grid, .instructors-grid, .testimonials-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-content h1 {
        font-size: 28px;
    }
    
    .hero-content p {
        font-size: 16px;
    }
    
    .btn {
        padding: 8px 16px;
        font-size: 14px;
    }
    
    .categories h2, .popular-courses h2, .learning-paths h2, .instructors h2, .testimonials h2, .faq h2, .subscribe h2 {
        font-size: 28px;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 30px;
    }
}