/* ========================================
   学习中心页面样式
   ======================================== */

/* ========== 分类导航 ========== */
.learn-nav {
    background-color: var(--white);
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-md) 0;
    position: sticky;
    top: 72px;
    z-index: 100;
}

.category-tabs {
    display: flex;
    gap: var(--spacing-sm);
    overflow-x: auto;
    padding-bottom: var(--spacing-xs);
}

.category-tab {
    padding: 10px 20px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-gray);
    background-color: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    cursor: pointer;
    white-space: nowrap;
    transition: all 0.2s ease;
}

.category-tab:hover {
    color: var(--primary-blue);
    border-color: var(--primary-blue);
}

.category-tab.active {
    color: var(--white);
    background-color: var(--primary-blue);
    border-color: var(--primary-blue);
}

/* ========== 推荐课程 ========== */
.featured-courses {
    padding: var(--spacing-3xl) 0;
    background-color: var(--bg-light);
}

.featured-courses .section-header {
    margin-bottom: var(--spacing-xl);
}

.featured-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xl);
}

.featured-card {
    background-color: var(--white);
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    display: flex;
    transition: all 0.3s ease;
}

.featured-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.featured-thumb {
    width: 200px;
    flex-shrink: 0;
    position: relative;
}

.thumb-placeholder {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, var(--bg-blue) 0%, var(--primary-blue) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
}

.thumb-placeholder span {
    font-size: 64px;
}

.thumb-placeholder.small span {
    font-size: 40px;
}

.featured-badge {
    position: absolute;
    top: var(--spacing-md);
    left: var(--spacing-md);
    padding: 4px 12px;
    font-size: 12px;
    font-weight: 600;
    color: var(--white);
    background-color: var(--primary-red);
    border-radius: var(--radius-sm);
}

.featured-badge.new {
    background-color: var(--success);
}

.featured-content {
    flex: 1;
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
}

.featured-meta {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
}

.meta-tag {
    font-size: 12px;
    color: var(--primary-blue);
    font-weight: 500;
}

.meta-lessons, .meta-duration {
    font-size: 12px;
    color: var(--text-light);
}

.featured-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
}

.featured-desc {
    font-size: 14px;
    color: var(--text-gray);
    line-height: 1.6;
    margin-bottom: var(--spacing-lg);
    flex: 1;
}

.featured-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.featured-stats {
    display: flex;
    gap: var(--spacing-md);
    font-size: 13px;
    color: var(--text-light);
}

/* ========== 课程列表 ========== */
.course-list {
    padding: var(--spacing-3xl) 0;
    background-color: var(--white);
}

.course-list .section-header {
    margin-bottom: var(--spacing-xl);
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
}

.course-card {
    background-color: var(--bg-light);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all 0.3s ease;
}

.course-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.course-thumb {
    height: 120px;
}

.course-thumb .thumb-placeholder {
    height: 100%;
}

.course-content {
    padding: var(--spacing-md);
}

.course-meta {
    display: flex;
    justify-content: space-between;
    margin-bottom: var(--spacing-sm);
}

.course-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: var(--spacing-xs);
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.course-desc {
    font-size: 13px;
    color: var(--text-gray);
    line-height: 1.5;
    margin-bottom: var(--spacing-md);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.course-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
}

.course-learners {
    font-size: 12px;
    color: var(--text-light);
}

.course-progress {
    font-size: 12px;
    color: var(--primary-blue);
    font-weight: 500;
}

.course-download {
    font-size: 12px;
    color: var(--primary-red);
}

/* ========== 学习须知 ========== */
.learn-tips {
    padding: var(--spacing-3xl) 0;
    background-color: var(--bg-light);
}

.learn-tips .section-title {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.tips-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
}

.tip-card {
    background-color: var(--white);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    text-align: center;
}

.tip-icon {
    font-size: 48px;
    margin-bottom: var(--spacing-md);
}

.tip-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: var(--spacing-sm);
}

.tip-desc {
    font-size: 14px;
    color: var(--text-gray);
    line-height: 1.6;
}

/* ========== 响应式 ========== */
@media (max-width: 1200px) {
    .course-grid {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .tips-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 992px) {
    .featured-grid {
        grid-template-columns: 1fr;
    }
    
    .featured-card {
        flex-direction: column;
    }
    
    .featured-thumb {
        width: 100%;
        height: 160px;
    }
    
    .course-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .page-header {
        padding: 100px 0 32px;
    }
    
    .page-title {
        font-size: 28px;
    }
    
    .category-tabs {
        padding: var(--spacing-sm) 0;
    }
    
    .category-tab {
        padding: 8px 16px;
        font-size: 13px;
    }
    
    .course-grid {
        grid-template-columns: 1fr;
    }
    
    .tips-grid {
        grid-template-columns: 1fr;
    }
}