/* 课程详情页容器 */
.course-detail-container {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 24px;
    padding-top: 24px;
}

/* 主内容区 */
.course-main {
    background: var(--bg-primary);
    border-radius: 12px;
    box-shadow: var(--card-shadow);
    overflow: hidden;
}

/* 视频播放区域 */
.video-section {
    width: 100%;
    background: #000;
}

.video-player {
    width: 100%;
    aspect-ratio: 16 / 9;
    background: #000;
    position: relative;
}

.video-player video {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.video-info {
    padding: 20px;
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
}

.video-info h1 {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.video-meta {
    display: flex;
    gap: 20px;
    color: var(--text-secondary);
    font-size: 14px;
}

.video-meta i {
    margin-right: 6px;
}

/* 课程标签页 */
.course-tabs {
    display: flex;
    padding: 0 20px;
    border-bottom: 1px solid var(--border-color);
    background: var(--bg-primary);
}

.tab-btn {
    padding: 16px 24px;
    border: none;
    background: none;
    font-size: 15px;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    position: relative;
    transition: all 0.3s;
}

.tab-btn:hover {
    color: var(--primary-color);
}

.tab-btn.active {
    color: var(--primary-color);
}

.tab-btn.active::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--primary-color);
}

/* 标签页内容 */
.tab-content {
    padding: 24px;
}

.tab-pane {
    display: none;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.tab-pane.active {
    display: block;
    opacity: 1;
}

/* 添加新的按钮样式 */
.add-note-btn,
.add-question-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 16px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 14px;
    transition: background 0.3s ease;
}

.add-note-btn:hover,
.add-question-btn:hover {
    background: var(--primary-dark);
}

.notes-container,
.qa-container {
    display: flex;
    flex-direction: column;
    gap: 16px;
    padding: 20px;
    background: var(--bg-secondary);
    border-radius: 8px;
}

/* 课程信息样式 */
.course-info h2 {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    margin: 24px 0 16px;
}

.course-info h2:first-child {
    margin-top: 0;
}

.course-info p {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 16px;
}

.course-benefits,
.target-audience {
    list-style: none;
    padding: 0;
}

.course-benefits li,
.target-audience li {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 12px;
    color: var(--text-secondary);
}

.course-benefits i,
.target-audience i {
    color: var(--primary-color);
    font-size: 16px;
}

.instructor-info {
    display: flex;
    gap: 16px;
    padding: 20px;
    background: var(--bg-secondary);
    border-radius: 12px;
}

.instructor-info img {
    width: 80px;
    height: 80px;
    border-radius: 40px;
    object-fit: cover;
}

.instructor-detail h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.instructor-detail p {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

/* 右侧课程目录 */
.course-sidebar {
    background: var(--bg-primary);
    border-radius: 12px;
    box-shadow: var(--card-shadow);
    height: fit-content;
    position: sticky;
    top: 88px;
}

.chapter-list {
    padding: 20px;
}

.chapter-list h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 16px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-primary);
}

.chapter {
    background: var(--bg-secondary);
    border-radius: 8px;
    padding: 16px;
}

.chapter-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.chapter-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
    margin: 0;
}

.chapter-info {
    font-size: 14px;
    color: var(--text-tertiary);
}

.chapter-duration {
    font-size: 13px;
    color: var(--text-secondary);
}

.chapter-lessons {
    padding-left: 12px;
}

.lesson {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 12px;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
}

.lesson:hover {
    background: var(--hover-bg);
}

.lesson.active {
    background: var(--hover-bg);
    color: var(--primary-color);
}

.lesson i {
    font-size: 16px;
    color: inherit;
    flex-shrink: 0;
    min-width: 16px;
    margin-top: 2px;
}

.lesson-title {
    flex: 1;
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.4;
}

.lesson.active .lesson-title {
    color: var(--primary-color);
}

.lesson-duration {
    font-size: 13px;
    color: var(--text-secondary);
    flex-shrink: 0;
    margin-left: 8px;
    margin-top: 2px;
}

/* 响应式设计 */
@media (max-width: 1200px) {
    .course-detail-container {
        grid-template-columns: 1fr 280px;
        gap: 20px;
    }
}

@media (max-width: 992px) {
    .course-detail-container {
        grid-template-columns: 1fr;
    }

    .course-sidebar {
        position: static;
        margin-bottom: 24px;
    }
}

@media (max-width: 768px) {
    .video-info h1 {
        font-size: 20px;
    }

    .course-tabs {
        padding: 0;
        overflow-x: auto;
    }

    .tab-btn {
        padding: 12px 16px;
        font-size: 14px;
        white-space: nowrap;
    }

    .tab-content {
        padding: 16px;
    }
}

/* 课程目录完整列表样式 */
.full-chapter-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

/* 笔记和问答区域的头部样式 */
.notes-header,
.qa-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.notes-header h2,
.qa-header h2 {
    margin: 0;
}

/* 空状态样式 */
.empty-state {
    text-align: center;
    padding: 40px 20px;
    color: var(--text-secondary);
}

.empty-state i {
    font-size: 48px;
    margin-bottom: 16px;
    color: var(--border-color);
}

.empty-state p {
    margin: 8px 0;
}

.empty-state .tip {
    font-size: 14px;
    color: var(--text-tertiary);
}

/* 笔记列表和问答列表样式 */
.notes-list,
.qa-list {
    background: var(--bg-secondary);
    border-radius: 8px;
    min-height: 200px;
}

/* 课时列表样式 */
.lesson-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.lesson-item {
    display: flex;
    align-items: center;
    padding: 12px;
    background: var(--bg-primary);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
}

.lesson-item:hover {
    background: var(--hover-color);
}

.lesson-icon {
    width: 24px;
    height: 24px;
    margin-right: 12px;
    color: var(--text-secondary);
}

.lesson-title {
    flex: 1;
    font-size: 14px;
    color: var(--text-primary);
}

.lesson-duration {
    font-size: 14px;
    color: var(--text-tertiary);
}

/* 推荐课程样式 */
.recommended-courses {
    padding: 20px;
}

.recommended-courses h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 16px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-primary);
}

.recommended-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.recommended-course {
    background: var(--bg-secondary);
    border-radius: 8px;
    overflow: hidden;
    transition: transform 0.2s;
}

.recommended-course:hover {
    transform: translateY(-2px);
}

.course-cover {
    width: 100%;
    aspect-ratio: 16 / 9;
    overflow: hidden;
}

.course-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.course-info {
    padding: 12px;
}

.course-info h4 {
    font-size: 14px;
    font-weight: 500;
    color: var(--text-primary);
    margin: 0 0 8px 0;
    line-height: 1.4;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 13px;
}

.students {
    color: var(--text-secondary);
}

.students i {
    margin-right: 4px;
}

/* 学习课程按钮 */
.study-btn {
    display: inline-block;
    padding: 6px 12px;
    background-color: var(--primary-color);
    color: white;
    border-radius: 4px;
    text-decoration: none;
    font-size: 13px;
    transition: background-color 0.2s;
}

.study-btn:hover {
    background-color: var(--primary-dark);
}