/* ===== RESET & BASE ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --primary: #6c47ff;
  --primary-light: #ede9ff;
  --primary-dark: #4f2fe0;
  --accent: #ff6b35;
  --bg: #f8f9fc;
  --surface: #ffffff;
  --border: #e4e7ef;
  --text: #1a1d2e;
  --text-muted: #6b7280;
  --radius: 14px;
  --radius-sm: 8px;
  --shadow: 0 2px 12px rgba(0,0,0,.07);
  --shadow-hover: 0 8px 28px rgba(108,71,255,.15);
  --transition: .2s ease;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

.hidden { display: none !important; }

.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ===== HEADER ===== */
.site-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 1px 8px rgba(0,0,0,.06);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 24px;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  flex-shrink: 0;
}

.logo-icon { font-size: 1.5rem; }

.logo-text {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--primary);
  letter-spacing: -.3px;
}

/* ===== BREADCRUMB ===== */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  font-size: .875rem;
}

.bc-item {
  color: var(--text-muted);
  cursor: pointer;
  transition: color var(--transition);
}

.bc-item:hover { color: var(--primary); }
.bc-item.active { color: var(--text); font-weight: 600; cursor: default; }

.bc-sep { color: var(--border); font-size: .75rem; }

/* ===== PAGE HERO ===== */
.page-hero {
  padding: 40px 0 28px;
}

.page-hero h1 {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -.5px;
  margin-bottom: 6px;
}

.page-hero p {
  color: var(--text-muted);
  font-size: 1rem;
}

/* ===== FILTER BAR ===== */
.filter-bar {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 28px;
}

.filter-btn {
  padding: 7px 18px;
  border-radius: 999px;
  border: 1.5px solid var(--border);
  background: var(--surface);
  color: var(--text-muted);
  font-size: .875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
}

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

.filter-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

/* ===== GRID ===== */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
  padding-bottom: 48px;
}

/* ===== CARD ===== */
.card {
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  overflow: hidden;
  cursor: pointer;
  transition: transform var(--transition), box-shadow var(--transition);
  display: flex;
  flex-direction: column;
}

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

/* ===== LOGO ICON SVG ===== */
.logo-icon {
  width: 28px;
  height: 28px;
  color: var(--primary);
  display: flex;
  align-items: center;
}
.logo-icon svg { width: 28px; height: 28px; }

/* ===== CARD THUMB ===== */
.card-thumb {
  width: 100%;
  aspect-ratio: 16/9;
  background: var(--primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  position: relative;
}

.card-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  transition: transform .3s ease;
}

.card:hover .card-thumb img {
  transform: scale(1.05);
}

.card-thumb-icon {
  color: var(--primary);
}
.card-thumb-icon svg { width: 52px; height: 52px; }

/* Badge icon */
.card-badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  margin-top: auto;
  padding: 3px 10px;
  border-radius: 999px;
  background: var(--primary-light);
  color: var(--primary);
  font-size: .75rem;
  font-weight: 600;
  width: fit-content;
}
.badge-icon { display: flex; align-items: center; }
.badge-icon svg { width: 13px; height: 13px; }

/* Empty state icon */
.empty-icon {
  color: var(--text-muted);
  margin-bottom: 8px;
}
.empty-icon svg { width: 48px; height: 48px; }

/* Lecture meta items */
.lec-meta-item {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}
.lec-meta-item svg { width: 13px; height: 13px; flex-shrink: 0; }

/* Lecture thumb overlay SVG */
.lec-thumb-overlay svg { width: 40px; height: 40px; }

/* Lec btn SVG */
.lec-btn svg { width: 15px; height: 15px; flex-shrink: 0; }

/* PDF popup item SVG */
.pdf-popup-item svg { width: 16px; height: 16px; flex-shrink: 0; }

.card-body {
  padding: 16px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.card-title {
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.4;
  color: var(--text);
}

.card-sub {
  font-size: .8rem;
  color: var(--text-muted);
}

.card-badge {
  display: inline-block;
  margin-top: auto;
  padding: 3px 10px;
  border-radius: 999px;
  background: var(--primary-light);
  color: var(--primary);
  font-size: .75rem;
  font-weight: 600;
  width: fit-content;
}

/* ===== SUBJECT CARD ===== */
.subject-card .card-thumb {
  font-size: 3.5rem;
}

/* ===== LECTURES LIST ===== */
.lectures-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
  padding-bottom: 48px;
}

/* Lecture Card */
.lec-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: visible;
  cursor: pointer;
  transition: transform var(--transition), box-shadow var(--transition);
  display: flex;
  flex-direction: column;
  position: relative;
}

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

/* Thumbnail */
.lec-thumb {
  width: 100%;
  aspect-ratio: 16/9;
  background: var(--primary-light);
  position: relative;
  overflow: hidden;
  flex-shrink: 0;
  border-radius: var(--radius) var(--radius) 0 0;
}

.lec-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  transition: transform .3s ease;
}

.lec-card:hover .lec-thumb img {
  transform: scale(1.05);
}

.lec-thumb-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,.4);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  color: #fff;
  opacity: 0;
  transition: opacity var(--transition);
}

.lec-card:hover .lec-thumb-overlay {
  opacity: 1;
}

.lec-num {
  position: absolute;
  top: 8px;
  left: 8px;
  background: rgba(0,0,0,.65);
  color: #fff;
  font-size: .75rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 6px;
  backdrop-filter: blur(4px);
}

/* Card body */
.lec-body {
  padding: 14px 16px 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  flex: 1;
}

.lec-title {
  font-size: .95rem;
  font-weight: 700;
  line-height: 1.4;
  color: var(--text);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.lec-meta {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  font-size: .78rem;
  color: var(--text-muted);
}

/* Buttons */
.lec-btns {
  display: flex;
  gap: 8px;
  margin-top: auto;
  padding-top: 4px;
}

.lec-btn {
  flex: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  font-size: .82rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  border: none;
  transition: all var(--transition);
}

.lec-btn-play {
  background: var(--primary);
  color: #fff;
}

.lec-btn-play:hover {
  background: var(--primary-dark);
}

.lec-btn-pdf {
  background: var(--primary-light);
  color: var(--primary);
  border: 1.5px solid var(--primary);
}

.lec-btn-pdf:hover {
  background: var(--primary);
  color: #fff;
}

/* PDF popup wrapper */
.pdf-wrap {
  flex: 1;
  position: relative;
}

.pdf-wrap .lec-btn-pdf {
  width: 100%;
}

/* Popup box */
.pdf-popup {
  display: none;
  position: fixed;
  bottom: 80px;
  left: 50%;
  transform: translateX(-50%);
  width: 260px;
  background: var(--surface);
  border: 1.5px solid var(--primary);
  border-radius: var(--radius);
  overflow: hidden;
  z-index: 9999;
  box-shadow: 0 8px 32px rgba(108,71,255,.25);
  animation: popIn .15s ease;
}

.pdf-popup.open {
  display: block;
}

@keyframes popIn {
  from { opacity: 0; transform: translateX(-50%) translateY(10px); }
  to   { opacity: 1; transform: translateX(-50%) translateY(0); }
}

.pdf-popup-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 11px 14px;
  font-size: .85rem;
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
  transition: background var(--transition);
  cursor: pointer;
}

.pdf-popup-item:first-child {
  border-bottom: 1px solid var(--border);
}

.pdf-popup-item:hover {
  background: var(--primary-light);
  color: var(--primary);
}

.icon-btn {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  border: 1.5px solid var(--border);
  background: var(--surface);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 1rem;
  text-decoration: none;
  transition: all var(--transition);
  color: var(--text-muted);
}

.icon-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--primary-light);
}

.play-btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  border: none;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  cursor: pointer;
  flex-shrink: 0;
  transition: background var(--transition), transform var(--transition);
}

.play-btn:hover {
  background: var(--primary-dark);
  transform: scale(1.1);
}

/* ===== PLAYER PAGE ===== */
.player-layout {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 24px;
  padding: 28px 0 48px;
  align-items: start;
}

@media (max-width: 900px) {
  .player-layout { grid-template-columns: 1fr; }
}

.player-wrapper {
  width: 100%;
  aspect-ratio: 16/9;
  border-radius: var(--radius);
  overflow: hidden;
  background: #000;
  box-shadow: var(--shadow);
}

.player-wrapper iframe {
  width: 100%;
  height: 100%;
  border: none;
  display: block;
}

.player-info {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-top: 16px;
}

.player-info h2 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 10px;
  line-height: 1.4;
}

.player-meta-row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.tag {
  padding: 4px 12px;
  border-radius: 999px;
  background: var(--primary-light);
  color: var(--primary);
  font-size: .8rem;
  font-weight: 500;
}

.player-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 9px 18px;
  border-radius: var(--radius-sm);
  font-size: .875rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition);
  border: none;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
}

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

.btn-outline {
  background: var(--surface);
  color: var(--primary);
  border: 1.5px solid var(--primary);
}

.btn-outline:hover {
  background: var(--primary-light);
}

/* ===== SIDEBAR ===== */
.player-sidebar {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.player-sidebar h3 {
  padding: 16px 20px;
  font-size: 1rem;
  font-weight: 700;
  border-bottom: 1px solid var(--border);
}

#sidebar-lectures {
  max-height: 600px;
  overflow-y: auto;
}

.sidebar-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  cursor: pointer;
  border-bottom: 1px solid var(--border);
  transition: background var(--transition);
}

.sidebar-item:last-child { border-bottom: none; }
.sidebar-item:hover { background: var(--bg); }

.sidebar-item.active {
  background: var(--primary-light);
  border-left: 3px solid var(--primary);
}

/* Sidebar thumbnail */
.sidebar-thumb {
  width: 72px;
  min-width: 72px;
  aspect-ratio: 16/9;
  border-radius: 6px;
  overflow: hidden;
  background: var(--primary-light);
  position: relative;
  flex-shrink: 0;
}

.sidebar-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.sidebar-thumb-fallback {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  font-size: .75rem;
  font-weight: 700;
  background: var(--primary-light);
}

.sidebar-play-icon {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,.4);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: .7rem;
  opacity: 0;
  transition: opacity var(--transition);
}

.sidebar-item:hover .sidebar-play-icon,
.sidebar-item.active .sidebar-play-icon {
  opacity: 1;
}

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

.sidebar-title {
  font-size: .82rem;
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  line-height: 1.3;
}

.sidebar-teacher {
  font-size: .73rem;
  color: var(--text-muted);
  margin-top: 2px;
}

/* ===== LOADING ===== */
.loading-state {
  grid-column: 1 / -1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 60px 0;
  color: var(--text-muted);
}

.spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin .7s linear infinite;
}

@keyframes spin { to { transform: rotate(360deg); } }

/* ===== EMPTY STATE ===== */
.empty-state {
  grid-column: 1 / -1;
  text-align: center;
  padding: 60px 0;
  color: var(--text-muted);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

/* ===== SCROLLBAR ===== */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--primary); }

/* ===== RESPONSIVE ===== */
@media (max-width: 900px) {
  .grid { grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); }
  .lectures-list { grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); }
}

@media (max-width: 640px) {
  .page-hero h1 { font-size: 1.5rem; }
  .page-hero { padding: 24px 0 18px; }
  .grid { grid-template-columns: 1fr 1fr; gap: 12px; }
  .lectures-list { grid-template-columns: 1fr 1fr; gap: 12px; }
  .lec-body { padding: 10px 12px 12px; }
  .lec-title { font-size: .88rem; }
  .lec-btn { font-size: .78rem; padding: 7px 8px; }
}

@media (max-width: 480px) {
  .grid { grid-template-columns: 1fr; gap: 12px; }
  .lectures-list { grid-template-columns: 1fr; gap: 12px; }
  .lec-card { flex-direction: column; }
  .lec-thumb {
    width: 100%;
    aspect-ratio: 16/9;
    align-self: auto;
    border-radius: 0;
  }
  .lec-body { padding: 10px 12px 14px; }
  .lec-title { font-size: .9rem; -webkit-line-clamp: 2; }
  .lec-btns { flex-direction: row; gap: 8px; }
  .lec-btn { font-size: .8rem; padding: 9px 10px; }
  .card-body { padding: 12px; }
  .card-title { font-size: .9rem; }
  .filter-bar { gap: 6px; }
  .filter-btn { padding: 5px 12px; font-size: .8rem; }
}