/* ============================================================
   COURSEVAULT — Course Detail Page Stylesheet
   ============================================================ */

/* ─── Course Hero ────────────────────────────────────────────── */
.course-hero {
  position: relative;
  overflow: hidden;
  padding: 60px 0 50px;
  min-height: 380px;
  display: flex;
  align-items: center;
}

.course-hero-bg {
  position: absolute;
  inset: 0;
}

.course-hero-bg-img {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
  filter: blur(60px) brightness(0.15);
  transform: scale(1.1);
}

.course-hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to bottom,
    rgba(8,12,20,0.5) 0%,
    rgba(8,12,20,0.85) 60%,
    rgba(8,12,20,1) 100%
  );
}

.course-hero-inner {
  position: relative;
  z-index: 1;
  display: flex;
  gap: 48px;
  align-items: flex-start;
}

.course-hero-content { flex: 1; max-width: 680px; }

.course-breadcrumb {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.course-breadcrumb a {
  color: var(--text-muted);
  text-decoration: none;
  transition: color var(--transition);
}

.course-breadcrumb a:hover { color: var(--accent); }

.course-breadcrumb i { font-size: 0.6rem; }

.course-category-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid var(--border-accent);
  padding: 4px 12px;
  border-radius: 100px;
  margin-bottom: 16px;
}

.course-hero-title {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4.5vw, 2.8rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 16px;
  line-height: 1.1;
  color: var(--text-primary);
}

.course-hero-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 24px;
  max-width: 580px;
}

.course-hero-stats {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.course-stat-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-secondary);
}

.course-stat-item i { color: var(--accent); font-size: 0.85rem; }

.course-stat-sep {
  width: 1px;
  height: 16px;
  background: var(--border);
}

.course-stat-featured { color: #fbbf24; }
.course-stat-featured i { color: #fbbf24; }

.course-hero-tags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.course-hero-thumb {
  flex-shrink: 0;
  width: 280px;
}

.course-hero-thumb img {
  width: 100%;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  box-shadow: 0 20px 60px rgba(0,0,0,0.5);
}

/* ─── Content sections ───────────────────────────────────────── */
.content-section-title {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 20px;
  color: var(--text-primary);
  display: flex;
  align-items: center;
}

.content-section-title i { color: var(--accent); }

/* ─── Course About ───────────────────────────────────────────── */
.course-about-block {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin-bottom: 32px;
}

.course-about-text {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.75;
}

.course-about-text p { margin-bottom: 14px; }
.course-about-text p:last-child { margin-bottom: 0; }

/* ─── Curriculum ─────────────────────────────────────────────── */
.curriculum-block { margin-bottom: 40px; }

.curriculum-sections {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

/* ─── Section ────────────────────────────────────────────────── */
.curriculum-section {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: border-color var(--transition);
}

.curriculum-section:target {
  border-color: var(--border-accent);
  box-shadow: var(--shadow-glow);
}

.section-header-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  cursor: pointer;
  background: var(--bg-surface);
  transition: background var(--transition);
  gap: 16px;
  user-select: none;
}

.section-header-bar:hover { background: var(--bg-elevated); }

.section-header-left {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  flex: 1;
  min-width: 0;
}

.section-number {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: var(--accent-dim);
  border: 1px solid var(--border-accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent);
  flex-shrink: 0;
}

.section-info { flex: 1; min-width: 0; }

.section-title-text {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 700;
  margin: 0 0 2px;
  color: var(--text-primary);
}

.section-subtitle-text {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.07em;
}

.section-header-right {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.section-meta-chip {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-muted);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  padding: 3px 9px;
  border-radius: 100px;
  white-space: nowrap;
}

.section-chevron {
  color: var(--text-muted);
  font-size: 0.85rem;
  transition: transform 0.25s ease;
}

.section-header-bar[aria-expanded="false"] .section-chevron {
  transform: rotate(-90deg);
}

.section-description-bar {
  padding: 12px 24px;
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--text-muted);
  font-style: italic;
}

/* ─── Module ─────────────────────────────────────────────────── */
.section-modules { padding: 16px; display: flex; flex-direction: column; gap: 12px; }

.curriculum-module {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.module-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  padding: 14px 18px;
  cursor: pointer;
  transition: background var(--transition);
  gap: 12px;
  user-select: none;
}

.module-header:hover { background: rgba(255,255,255,0.02); }

.module-header-left {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  flex: 1;
}

.module-icon {
  color: var(--accent);
  font-size: 1rem;
  margin-top: 2px;
  flex-shrink: 0;
}

.module-title-text {
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 700;
  margin: 0;
  color: var(--text-primary);
}

.module-desc-text {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin: 4px 0 0;
  line-height: 1.4;
}

.module-header-right {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.module-lesson-count {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-muted);
  white-space: nowrap;
}

.module-chevron {
  color: var(--text-muted);
  font-size: 0.8rem;
  transition: transform 0.25s ease;
}

.module-header[aria-expanded="false"] .module-chevron {
  transform: rotate(-90deg);
}

/* ─── Lesson Card ────────────────────────────────────────────── */
.module-lessons {
  padding: 0 4px 8px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.lessons-empty, .modules-empty {
  padding: 16px 18px;
  font-size: 0.8rem;
  color: var(--text-dim);
  display: flex;
  align-items: center;
  gap: 8px;
}

.lesson-card {
  background: var(--bg-base);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  transition: border-color var(--transition);
}

.lesson-card:hover { border-color: rgba(255,255,255,0.1); }

.lesson-card-header {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px 16px;
  cursor: pointer;
}

.lesson-number {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--text-muted);
  flex-shrink: 0;
  margin-top: 2px;
}

.lesson-info { flex: 1; min-width: 0; }

.lesson-title {
  font-family: var(--font-display);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin: 0 0 5px;
  line-height: 1.3;
}

.lesson-meta {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.lesson-date-chip {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--text-muted);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  padding: 2px 8px;
  border-radius: 100px;
}

.lesson-date-chip i { color: #fbbf24; }

.lesson-video-chip {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: #ff6060;
  background: rgba(255,0,0,0.08);
  border: 1px solid rgba(255,0,0,0.2);
  padding: 2px 8px;
  border-radius: 100px;
}

.lesson-expand-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 2px;
  font-size: 0.75rem;
  transition: color var(--transition), transform 0.2s;
  flex-shrink: 0;
  margin-top: 4px;
}

.lesson-expand-btn:hover { color: var(--text-secondary); }
.lesson-expand-btn[aria-expanded="true"] i { transform: rotate(180deg); display: inline-block; }

/* ─── Lesson Detail Body ─────────────────────────────────────── */
.lesson-detail-body {
  padding: 0 16px 16px 52px;
  border-top: 1px solid var(--border);
}

.lesson-summary {
  padding-top: 14px;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.75;
  white-space: pre-wrap;
}

/* ─── YouTube Block ──────────────────────────────────────────── */
.lesson-youtube-block {
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

.youtube-block-header {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.youtube-icon { color: #ff4040; font-size: 1rem; }

.youtube-embed-wrap {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  background: #000;
}

.youtube-embed-wrap iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: none;
}

/* ─── Sidebar ────────────────────────────────────────────────── */
.sticky-sidebar {
  position: sticky;
  top: 90px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.sidebar-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 20px;
}

.sidebar-card-title {
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 14px;
  color: var(--text-primary);
}

.course-overview-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.course-overview-list li {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.course-overview-list li:last-child { border-bottom: none; }
.course-overview-list li i { color: var(--accent); font-size: 0.9rem; flex-shrink: 0; }

.sidebar-tags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

/* ─── Responsive ─────────────────────────────────────────────── */
@media (max-width: 991px) {
  .course-hero-inner { flex-direction: column; }
  .course-hero-thumb { width: 100%; max-width: 360px; }
  .lesson-detail-body { padding-left: 16px; }
  .sticky-sidebar { position: static; }
}

@media (max-width: 767px) {
  .course-hero { padding: 40px 0 32px; min-height: unset; }
  .course-hero-title { font-size: 1.7rem; }
  .section-header-bar { padding: 16px; }
  .section-meta-chip { display: none; }
  .module-header { padding: 12px 14px; }
  .lesson-card-header { padding: 10px 12px; }
  .lesson-detail-body { padding: 0 12px 12px; }
  .course-about-block { padding: 20px; }
}