:root {
  --bg: #f4f6f9;
  --card: #ffffff;
  --primary: #4361ee;
  --primary-light: #eef0ff;
  --text: #1a1a2e;
  --muted: #6b7280;
  --border: #e5e7eb;
  --radius: 12px;
  --shadow: 0 2px 12px rgba(0,0,0,0.06);
}

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

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

header {
  background: linear-gradient(135deg, #4361ee, #3a0ca3);
  color: #fff;
  padding: 48px 24px;
  text-align: center;
}

header h1 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 8px;
}

header p {
  opacity: 0.85;
  font-size: 1rem;
}

.container {
  max-width: 860px;
  margin: 0 auto;
  padding: 32px 16px;
}

.session-card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  margin-bottom: 28px;
  overflow: hidden;
  border: 1px solid var(--border);
}

.session-header {
  padding: 20px 24px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 16px;
  user-select: none;
  transition: background 0.15s;
}

.session-header:hover { background: var(--primary-light); }

.session-number {
  background: var(--primary);
  color: #fff;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.9rem;
  flex-shrink: 0;
}

.session-meta { flex: 1; }

.session-meta h2 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 2px;
}

.session-meta .date {
  font-size: 0.82rem;
  color: var(--muted);
}

.toggle-icon {
  font-size: 1.2rem;
  color: var(--muted);
  transition: transform 0.25s;
  flex-shrink: 0;
}

.session-header.active .toggle-icon { transform: rotate(180deg); }

.session-body {
  padding: 0 24px 24px;
  display: none;
}

.session-body.open { display: block; }

.notes {
  background: var(--primary-light);
  border-radius: 8px;
  padding: 16px 20px;
  margin-bottom: 20px;
  font-size: 0.92rem;
  line-height: 1.7;
  color: #2d3142;
}

.section-label {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin-bottom: 12px;
}

.audio-list { margin-bottom: 24px; }

.audio-item {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.audio-item .label {
  font-size: 0.82rem;
  color: var(--muted);
  min-width: 180px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

audio {
  height: 36px;
  flex: 1;
  min-width: 200px;
  border-radius: 8px;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
  gap: 16px;
  margin-bottom: 8px;
}

.video-wrapper {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;
  border-radius: 8px;
  overflow: hidden;
  background: #000;
}

.video-wrapper iframe {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  border: none;
}

.drive-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--primary-light);
  color: var(--primary);
  padding: 10px 16px;
  border-radius: 8px;
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 500;
  transition: background 0.15s;
}

.drive-link:hover { background: #dce1ff; }

.no-content {
  color: var(--muted);
  font-size: 0.88rem;
  font-style: italic;
}

@media (max-width: 600px) {
  header { padding: 32px 16px; }
  header h1 { font-size: 1.5rem; }
  .session-header { padding: 16px; }
  .session-body { padding: 0 16px 16px; }
  .audio-item { flex-direction: column; align-items: flex-start; }
  .audio-item .label { min-width: unset; }
  .video-grid { grid-template-columns: 1fr; }
}