.page-course-detail {
  background: #f5f6f8;
}

.page-course-detail .main-content {
  background: #f5f6f8;
}

.course-detail-banner {
  width: 100%;
  line-height: 0;
  overflow: hidden;
}

.course-detail-banner img {
  width: 100%;
  height: auto;
  display: block;
  max-height: 280px;
  object-fit: cover;
}

.course-detail-breadcrumb {
  background: transparent;
  padding: var(--spacing-lg) 0 var(--spacing-md);
}

.course-detail-breadcrumb__inner {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.course-detail-breadcrumb__icon {
  width: 26px;
  height: 26px;
  object-fit: contain;
  flex-shrink: 0;
}

.course-detail-breadcrumb__list {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--spacing-md);
  font-size: var(--font-size-base);
  color: var(--color-text-light);
}

.course-detail-breadcrumb__list li {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.course-detail-breadcrumb__list li:not(:last-child)::after {
  content: ">";
  color: var(--color-text-muted);
}

.course-detail-breadcrumb__list a:hover {
  color: var(--color-primary);
}

.course-detail-breadcrumb__list li:last-child span {
  color: var(--color-text);
  max-width: 420px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.course-detail-main {
  padding: var(--spacing-lg) 0 var(--spacing-3xl);
}

.detail-layout {
  display: grid;
  grid-template-columns: 1fr 360px;
  gap: var(--spacing-xl);
  align-items: start;
}

.detail-main {
  background: #ffffff;
  padding: var(--spacing-xl);
}

.detail-main__cover {
  overflow: hidden;
  margin-bottom: var(--spacing-xl);
  aspect-ratio: 16/9;
  background: #f0f0f0;
}

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

.detail-main__title {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  margin-bottom: var(--spacing-md);
  line-height: 1.4;
}

.detail-main__meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-lg);
  font-size: var(--font-size-sm);
  color: var(--color-text-light);
  margin-bottom: var(--spacing-lg);
}

.detail-main__tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-xl);
}

.detail-tabs {
  display: flex;
  border-bottom: 2px solid var(--color-border);
  margin-bottom: var(--spacing-xl);
}

.detail-tab {
  padding: var(--spacing-md) var(--spacing-xl);
  font-weight: 500;
  color: var(--color-text-light);
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.detail-tab--active {
  color: #58a6f7;
  border-bottom-color: #58a6f7;
}

.detail-tab-content {
  display: none;
}

.detail-tab-content--active {
  display: block;
}

.detail-desc {
  line-height: 1.8;
  color: var(--color-text-light);
}

.detail-desc h2 {
  font-size: var(--font-size-xl);
  color: var(--color-text);
  margin: var(--spacing-xl) 0 var(--spacing-md);
}

.detail-list {
  list-style: disc;
  padding-left: var(--spacing-xl);
  color: var(--color-text-light);
}

.detail-list li {
  margin-bottom: var(--spacing-sm);
}

.chapter-list {
  border: 1px solid var(--color-border-light);
  overflow: hidden;
}

.chapter-item {
  border-bottom: 1px solid var(--color-border-light);
}

.chapter-item:last-child {
  border-bottom: none;
}

.chapter-item__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: var(--spacing-lg);
  background: var(--color-bg-light);
  border: none;
  font: inherit;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
}

.chapter-item__lessons {
  display: none;
}

.chapter-item--open .chapter-item__lessons {
  display: block;
}

.lesson-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md) var(--spacing-lg) var(--spacing-md) var(--spacing-2xl);
  font-size: var(--font-size-sm);
  border-top: 1px solid var(--color-border-light);
  transition: background var(--transition-fast);
}

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

.lesson-item__title {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.lesson-item__title a:hover {
  color: #58a6f7;
}

.lesson-item__actions {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  flex-shrink: 0;
}

.lesson-item__duration {
  color: var(--color-text-muted);
  white-space: nowrap;
}

.lesson-item__play-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 52px;
  height: 28px;
  padding: 0 12px;
  background: #58a6f7;
  color: #ffffff;
  font-size: var(--font-size-xs);
  border-radius: var(--radius-sm);
  transition: background var(--transition-fast);
  white-space: nowrap;
}

.lesson-item__play-btn:hover {
  background: #3d96f5;
  color: #ffffff;
}

.lesson-item__free {
  font-size: var(--font-size-xs);
  color: var(--color-success);
}

.lesson-item__pending {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

.lesson-item__play-btn--disabled {
  background: #e5e7eb;
  color: #9ca3af;
  cursor: not-allowed;
}

.detail-sidebar {
  position: sticky;
  top: var(--spacing-lg);
}

.course-sidebar-card {
  background: #ffffff;
  padding: var(--spacing-xl);
  border: 1px solid var(--color-border-light);
}

.course-sidebar-card__info {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  font-size: var(--font-size-sm);
  color: var(--color-text-light);
  margin-bottom: var(--spacing-xl);
  padding-bottom: var(--spacing-lg);
  border-bottom: 1px solid var(--color-border-light);
}

.course-sidebar-card__actions {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.course-sidebar-card__actions .btn {
  width: 100%;
}

.course-sidebar-card__actions .btn--primary {
  background: linear-gradient(135deg, #58a6f7, #7ec8fa);
}

.course-sidebar-card__actions .btn--primary:hover {
  background: linear-gradient(135deg, #4d9ef7, #6db8fa);
}

.teacher-mini {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  margin-top: var(--spacing-xl);
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--color-border-light);
  color: inherit;
  transition: color var(--transition-fast);
}

.teacher-mini:hover {
  color: #58a6f7;
}

.teacher-mini__avatar {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  overflow: hidden;
  flex-shrink: 0;
}

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

.teacher-mini__name {
  font-weight: 600;
}

.teacher-mini__title {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

@media (max-width: 1024px) {
  .detail-layout {
    grid-template-columns: 1fr;
  }

  .detail-sidebar {
    position: static;
  }
}

@media (max-width: 768px) {
  .course-detail-banner img {
    max-height: 160px;
  }

  .detail-main {
    padding: var(--spacing-lg);
  }

  .detail-main__title {
    font-size: var(--font-size-xl);
  }
}