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

body {
    font-family: 'Arial', sans-serif;
    line-height: 1.6;
    color: #333;
    background: #f8fafc;
}

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

/* 头部导航 */
.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 15px 0;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand h1 a {
    color: white;
    text-decoration: none;
    font-size: 24px;
    font-weight: 600;
}
}

.nav-link:hover,
.nav-link.active {
    opacity: 0.8;
}

.nav-actions {
    display: flex;
    gap: 15px;
}

.btn-primary {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    padding: 8px 20px;
    border-radius: 20px;
    text-decoration: none;
    font-weight: 500;
    transition: background 0.3s ease;
}

.btn-primary:hover {
    background: rgba(255, 255, 255, 0.3);
}

.btn-secondary {
    color: white;
    text-decoration: none;
    padding: 8px 20px;
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: 20px;
    transition: background 0.3s ease;
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
}

/* 主要内容 */
.main {
    padding: 40px 0;
    min-height: calc(100vh - 200px);
}

.page-header {
    text-align: center;
    margin-bottom: 40px;
}

.page-header h1 {
    color: #1e293b;
    font-size: 36px;
    margin-bottom: 10px;
}

.page-header p {
    color: #64748b;
    font-size: 18px;
}

/* 筛选区域 */
.filter-section {
    margin-bottom: 40px;
}

.filter-bar {
    background: white;
    padding: 25px;
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
}

.category-filter {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 8px 16px;
    border: 2px solid #e2e8f0;
    border-radius: 20px;
    text-decoration: none;
    color: #64748b;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.3s ease;
}

.filter-btn:hover,
.filter-btn.active {
    border-color: #8b5cf6;
    background: #8b5cf6;
    color: white;
}

.search-form {
    display: flex;
    gap: 10px;
}

.search-form input {
    padding: 10px 15px;
    border: 2px solid #e2e8f0;
    border-radius: 25px;
    font-size: 14px;
    width: 250px;
    transition: border-color 0.3s ease;
}

.search-form input:focus {
    outline: none;
    border-color: #8b5cf6;
}

.search-btn {
    background: #8b5cf6;
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 25px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    transition: background 0.3s ease;
}

.search-btn:hover {
    background: #7c3aed;
}

/* 课程网格 */
.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 25px;
    margin-bottom: 40px;
}

.course-card {
    background: white;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.course-image {
    position: relative;
    height: 200px;
    overflow: hidden;
}

.course-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s ease;
}

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

.course-placeholder {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #8b5cf6, #a855f7);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 48px;
}

.course-badge {
    position: absolute;
    top: 15px;
    right: 15px;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 600;
}

.course-badge.free {
    background: #10b981;
    color: white;
}

.course-badge.discount {
    background: #ef4444;
    color: white;
}

.course-content {
    padding: 20px;
}

.course-category {
    color: #8b5cf6;
    font-size: 12px;
    font-weight: 600;
    text-transform: uppercase;
    margin-bottom: 8px;
}

.course-title {
    margin-bottom: 10px;
}

.course-title a {
    color: #1e293b;
    text-decoration: none;
    font-size: 18px;
    font-weight: 600;
    line-height: 1.4;
    transition: color 0.3s ease;
}

.course-title a:hover {
    color: #8b5cf6;
}

.course-description {
    color: #64748b;
    font-size: 14px;
    line-height: 1.6;
    margin-bottom: 15px;
}

.course-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-bottom: 20px;
    font-size: 12px;
    color: #94a3b8;
}

.course-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 15px;
    border-top: 1px solid #f1f5f9;
}

.course-price {
    display: flex;
    align-items: center;
    gap: 8px;
}

.price-current {
    color: #ef4444;
    font-size: 18px;
    font-weight: 700;
}

.price-original {
    color: #94a3b8;
    font-size: 14px;
    text-decoration: line-through;
}

.price-free {
    color: #10b981;
    font-size: 16px;
    font-weight: 700;
}

.btn-enroll {
    background: #8b5cf6;
    color: white;
    padding: 8px 16px;
    border-radius: 8px;
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
    transition: background 0.3s ease;
}

.btn-enroll:hover {
    background: #7c3aed;
}

/* 分页 */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 10px;
    margin-top: 40px;
}

.page-btn {
    padding: 10px 15px;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    text-decoration: none;
    color: #64748b;
    font-size: 14px;
    transition: all 0.3s ease;
}

.page-btn:hover {
    background: #f8fafc;
    border-color: #8b5cf6;
    color: #8b5cf6;
}

.page-btn.active {
    background: #8b5cf6;
    border-color: #8b5cf6;
    color: white;
}

/* 空状态 */
.empty-state {
    text-align: center;
    padding: 80px 20px;
}

.empty-icon {
    font-size: 64px;
    opacity: 0.3;
    margin-bottom: 20px;
}

.empty-state h3 {
    color: #1e293b;
    margin-bottom: 10px;
    font-size: 24px;
}

.empty-state p {
    color: #64748b;
    margin-bottom: 30px;
    font-size: 16px;
}

/* 底部 */
.footer {
    background: #1e293b;
    color: white;
    text-align: center;
    padding: 30px 0;
    margin-top: 60px;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .header .container {
        flex-direction: column;
        gap: 15px;
    }
    
    .nav-menu {
        gap: 20px;
    }
    
    .page-header h1 {
        font-size: 28px;
    }
    
    .filter-bar {
        flex-direction: column;
        align-items: stretch;
        gap: 20px;
    }
    
    .category-filter {
        justify-content: center;
    }
    
    .search-form input {
        width: 100%;
    }
    
    .courses-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .course-meta {
        flex-direction: column;
        gap: 8px;
    }
    
    .pagination {
        flex-wrap: wrap;
        gap: 5px;
    }
}

/* 动画效果 */
.course-card {
    animation: fadeInUp 0.3s ease-out;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 加载状态 */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 60px;
    font-size: 16px;
    color: #64748b;
}

.loading::before {
    content: '';
    width: 20px;
    height: 20px;
    border: 2px solid #e2e8f0;
    border-top-color: #8b5cf6;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-right: 10px;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}/* 
页面副标题样式 */
.page-subtitle {
    color: #64748b;
    font-size: 16px;
    margin-top: 10px;
    margin-bottom: 0;
    line-height: 1.6;
}

/* 响应式页面标题 */
@media (max-width: 768px) {
    .page-header h1 {
        font-size: 24px;
    }
    
    .page-subtitle {
        font-size: 14px;
    }
}

/* 筛选器响应式优化 */
@media (max-width: 768px) {
    .filter-bar {
        flex-direction: column;
        gap: 15px;
    }
    
    .category-filter {
        flex-wrap: wrap;
        gap: 8px;
    }
    
    .filter-btn {
        font-size: 13px;
        padding: 6px 12px;
    }
}