/* ========================================
   Lesson Selection Modal - Design System
   ======================================== */
:root {
  --ls-font: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --ls-primary: #0d9488;
  --ls-primary-dark: #0f766e;
  --ls-primary-light: #14b8a6;
  --ls-accent: #f59e0b;
  --ls-bg: #f8fafc;
  --ls-surface: #ffffff;
  --ls-text: #1e293b;
  --ls-text-muted: #64748b;
  --ls-border: #e2e8f0;
  --ls-radius: 12px;
  --ls-radius-lg: 16px;
  --ls-radius-xl: 20px;
  --ls-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.08), 0 2px 4px -2px rgba(0, 0, 0, 0.04);
  --ls-shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
  --ls-shadow-glow: 0 0 40px rgba(13, 148, 136, 0.15);
  --ls-transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --ls-spacing-xs: 4px;
  --ls-spacing-sm: 8px;
  --ls-spacing-md: 16px;
  --ls-spacing-lg: 24px;
  --ls-spacing-xl: 32px;
  --ls-touch-min: 44px;
}

/* Category-specific gradients */
.category-kids { --cat-gradient: linear-gradient(145deg, #0d9488 0%, #14b8a6 50%, #2dd4bf 100%); --cat-glow: rgba(13, 148, 136, 0.35); }
.category-teens { --cat-gradient: linear-gradient(145deg, #7c3aed 0%, #8b5cf6 50%, #a78bfa 100%); --cat-glow: rgba(124, 58, 237, 0.35); }
.category-adults { --cat-gradient: linear-gradient(145deg, #1e40af 0%, #2563eb 50%, #3b82f6 100%); --cat-glow: rgba(30, 64, 175, 0.35); }
.category-ielts { --cat-gradient: linear-gradient(145deg, #b45309 0%, #d97706 50%, #f59e0b 100%); --cat-glow: rgba(180, 83, 9, 0.35); }

/* Lesson viewer and star UI */
.margin-top-140 { margin-top: 140px; }
.position-relative { position: relative; }

.choose-lesson-section {
  min-height: calc(100vh - 80px);
  padding: 24px 20px 48px;
}

.choose-lesson-section .container {
  max-width: 1280px;
  margin: 0 auto;
}

.lesson-viewer-wrap {
  position: relative;
}

.lesson-viewer-wrap-inner {
  position: relative;
}

.btn-report-mistake {
  position: absolute;
  bottom: 16px;
  right: 16px;
  z-index: 20;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  font-size: 0.9rem;
  font-weight: 600;
  font-family: var(--ls-font);
  color: white;
  background: rgba(220, 38, 38, 0.9);
  border: 1px solid rgba(220, 38, 38, 0.5);
  border-radius: var(--ls-radius);
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  transition: background 0.2s, transform var(--ls-transition);
}

.btn-report-mistake:hover {
  background: #dc2626;
  transform: translateY(-2px);
}

.report-lesson-label {
  font-weight: 600;
  color: var(--ls-primary);
  margin: 0;
  word-wrap: break-word;
  overflow-wrap: break-word;
  word-break: break-word;
  line-height: 1.4;
}

.report-mistake-hint {
  font-size: 0.95rem;
  color: var(--ls-text-muted);
  margin: 0 0 16px;
  line-height: 1.5;
}

/* Report Mistake Modal */
.report-mistake-modal {
  z-index: 9999;
  padding: 20px;
}

.report-mistake-modal .modal-backdrop {
  position: absolute;
  inset: 0;
  z-index: 0;
  background: rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

.report-mistake-modal .modal-dialog {
  position: relative;
  z-index: 1;
  isolation: isolate;
}

.report-mistake-dialog {
  width: 100%;
  max-width: 520px;
  max-height: min(90vh, 560px);
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg), 0 0 0 1px var(--ls-border);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  animation: modalScaleIn 0.25s ease-out;
}

.report-mistake-modal .modal-content {
  display: flex;
  flex-direction: column;
  max-height: 100%;
  min-height: 0;
}

.report-mistake-modal .modal-header {
  flex-shrink: 0;
  padding: 20px 24px;
  background: linear-gradient(135deg, #dc2626 0%, #b91c1c 100%);
  color: white;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.report-mistake-modal .modal-title {
  margin: 0;
  font-size: 1.15rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 10px;
}

.report-mistake-modal .modal-close {
  width: 40px;
  height: 40px;
  min-width: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.2);
  border: none;
  color: white;
  border-radius: var(--ls-radius);
  cursor: pointer;
  font-size: 1rem;
  transition: background var(--ls-transition);
}

.report-mistake-modal .modal-close:hover {
  background: rgba(255, 255, 255, 0.3);
}

.report-mistake-modal .modal-body {
  flex: 1;
  min-height: 0;
  overflow-y: auto;
  padding: 24px;
}

.report-mistake-lesson {
  margin-bottom: 16px;
  padding: 12px 16px;
  background: #fef2f2;
  border: 1px solid #fecaca;
  border-radius: var(--ls-radius);
}

.report-mistake-lesson-label {
  display: block;
  font-size: 0.8rem;
  font-weight: 600;
  color: #b91c1c;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 4px;
}

.report-mistake-modal .report-lesson-label {
  font-size: 0.95rem;
  color: var(--ls-text);
}

.report-mistake-modal .report-mistake-hint {
  margin-bottom: 20px;
}

.report-mistake-modal .form-group {
  margin: 0;
}

.report-mistake-modal .form-group textarea {
  width: 100%;
  min-height: 120px;
  padding: 14px 16px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  font-size: 0.95rem;
  font-family: var(--ls-font);
  line-height: 1.5;
  resize: vertical;
  box-sizing: border-box;
}

.report-mistake-modal .form-group textarea:focus {
  outline: none;
  border-color: #dc2626;
  box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.15);
}

.report-mistake-modal .form-group textarea::placeholder {
  color: var(--ls-text-muted);
}

.report-mistake-modal .modal-footer {
  flex-shrink: 0;
  display: flex;
  gap: 12px;
  justify-content: flex-end;
  padding: 16px 24px;
  background: var(--ls-bg);
  border-top: 1px solid var(--ls-border);
}

.btn-report-cancel {
  padding: 12px 24px;
  min-height: 44px;
  background: var(--ls-surface);
  color: var(--ls-text);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  font-family: var(--ls-font);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background var(--ls-transition), border-color var(--ls-transition);
}

.btn-report-cancel:hover {
  background: var(--ls-bg);
  border-color: var(--ls-text-muted);
}

.btn-report-submit {
  padding: 12px 24px;
  min-height: 44px;
  background: linear-gradient(135deg, #dc2626 0%, #b91c1c 100%);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  font-family: var(--ls-font);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  box-shadow: 0 4px 12px rgba(220, 38, 38, 0.3);
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}

.btn-report-submit:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(220, 38, 38, 0.4);
  color: white;
}

/* Shared nav toolbar button base */
.btn-browser,
.btn-phonics-track,
.btn-video,
.btn-games,
.btn-whiteboard,
.btn-question-gen {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: clamp(32px, 3.2vw, 44px);
  height: clamp(32px, 3.2vw, 44px);
  margin-left: clamp(2px, 0.5vw, 8px);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  flex-shrink: 1;
  font-size: clamp(0.8rem, 1.1vw, 1rem);
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}

/* Browser button */
.btn-browser {
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
}
.btn-browser:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(13, 148, 136, 0.4);
}

/* Phonics Track (iframe hub) */
.btn-phonics-track {
  background: linear-gradient(135deg, #0e7490 0%, #0891b2 50%, #0d9488 100%);
}
.btn-phonics-track:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(8, 145, 178, 0.45);
}

/* Video library button */
.btn-video {
  background: linear-gradient(135deg, #7c3aed 0%, #6d28d9 100%);
}
.btn-video:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(124, 58, 237, 0.4);
}

/* Games (Online Teacher Game) */
.btn-games {
  background: #6366f1;
  font-size: clamp(1rem, 1.35vw, 1.25rem);
  line-height: 1;
  padding: 0;
}
.btn-games .btn-games-emoji {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
}
.btn-games:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(99, 102, 241, 0.45);
}

/* Whiteboard button */
.btn-whiteboard {
  background: linear-gradient(135deg, #0ea5e9 0%, #0284c7 100%);
}
.btn-whiteboard:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(14, 165, 233, 0.4);
}

/* Question Generator button */
.btn-question-gen {
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  font-weight: 700;
}
.btn-question-gen:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.45);
}

/* More tools dropdown trigger - small black triangle */
.nav-tools-more-wrap {
  position: relative;
  display: inline-flex;
  align-items: center;
  margin-left: clamp(2px, 0.5vw, 8px);
}

.btn-more-tools {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: clamp(24px, 2.5vw, 32px);
  height: clamp(32px, 3.2vw, 44px);
  padding: 0;
  color: #1e293b;
  background: transparent;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  font-size: clamp(0.7rem, 1vw, 0.9rem);
  transition: background var(--ls-transition), color var(--ls-transition);
}

.btn-more-tools:hover {
  background: rgba(30, 41, 59, 0.08);
  color: #0f172a;
}

.btn-more-tools[aria-expanded="true"] {
  background: rgba(30, 41, 59, 0.12);
}

.more-tools-dropdown {
  display: none;
  position: absolute;
  top: calc(100% + 6px);
  left: 0;
  min-width: 160px;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-lg);
  box-shadow: var(--ls-shadow-lg);
  border: 1px solid var(--ls-border);
  padding: 6px;
  z-index: 1100;
}

.more-tools-dropdown.show {
  display: block;
  animation: viewFadeIn 0.2s ease-out;
}

.more-tools-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  color: var(--ls-text);
  font-size: 0.9rem;
  text-decoration: none;
  border-radius: var(--ls-radius);
  transition: background var(--ls-transition), color var(--ls-transition);
}

.more-tools-item:hover {
  background: var(--ls-bg);
  color: var(--ls-primary);
}

.more-tools-item i {
  width: 18px;
  flex-shrink: 0;
  opacity: 0.85;
}

button.more-tools-item.more-tools-item-btn {
  width: 100%;
  border: none;
  background: none;
  font: inherit;
  font-family: var(--ls-font);
  text-align: left;
  cursor: pointer;
}

/* Report mistake button in navbar - shown when a lesson is loaded */
.btn-report-mistake-nav {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-left: 8px;
  padding: 8px 14px;
  font-size: 0.9rem;
  font-weight: 600;
  color: #dc2626;
  background: rgba(220, 38, 38, 0.1);
  border: 1px solid rgba(220, 38, 38, 0.3);
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: transform var(--ls-transition), background var(--ls-transition);
}

.btn-report-mistake-nav:hover {
  background: rgba(220, 38, 38, 0.15);
  transform: translateY(-2px);
}

.btn-report-mistake.hidden {
  display: none !important;
}

/* Annotation tip modal */
.annotation-tip-modal {
  display: none;
  align-items: center;
  justify-content: center;
  position: fixed;
  inset: 0;
  z-index: 9999;
  padding: 20px;
  background: rgba(0, 0, 0, 0.4);
}
.annotation-tip-modal.show {
  display: flex;
}
.annotation-tip-dialog {
  max-width: 480px;
  width: 100%;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg);
}
.annotation-tip-modal .modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  border-bottom: 1px solid var(--ls-border);
}
.annotation-tip-modal .modal-title {
  margin: 0;
  font-size: 1.15rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ls-text);
}
.annotation-tip-modal .modal-title i {
  color: #059669;
}
.annotation-tip-modal .modal-close {
  background: none;
  border: none;
  font-size: 1.25rem;
  cursor: pointer;
  color: var(--ls-text-muted);
  padding: 4px;
}
.annotation-tip-modal .modal-close:hover {
  color: var(--ls-text);
}
.annotation-tip-body {
  padding: 24px;
}
.annotation-tip-body p {
  margin: 0 0 16px;
  font-size: 0.95rem;
  line-height: 1.6;
  color: var(--ls-text);
}
.annotation-tip-body p:last-of-type {
  margin-bottom: 20px;
}
.btn-annotation-extension {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  font-family: var(--ls-font);
  color: white;
  background: linear-gradient(135deg, #059669 0%, #047857 100%);
  border-radius: var(--ls-radius);
  text-decoration: none;
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}
.btn-annotation-extension:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(5, 150, 105, 0.4);
  color: white;
}
.annotation-tip-modal .modal-footer {
  padding: 16px 24px;
  border-top: 1px solid var(--ls-border);
  display: flex;
  justify-content: flex-end;
}

/* Video overlay */
.video-overlay {
  position: absolute;
  inset: 0;
  z-index: 101;
  display: flex;
  flex-direction: column;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg);
  border: 1px solid var(--ls-border);
  overflow: hidden;
}
.video-overlay.hidden {
  display: none;
}

/* Whiteboard overlay */
.whiteboard-overlay {
  position: absolute;
  inset: 0;
  z-index: 100;
  display: flex;
  flex-direction: column;
  background: rgba(248, 250, 252, 0.98);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg);
  border: 1px solid var(--ls-border);
  overflow: hidden;
}
.whiteboard-overlay.hidden {
  display: none;
}

/* ── Question Generator overlay ── */
.question-gen-overlay {
  position: absolute;
  inset: 0;
  z-index: 100;
  display: flex;
  flex-direction: column;
  background: rgba(248, 250, 252, 0.98);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg);
  border: 1px solid var(--ls-border);
  overflow: hidden;
}
.question-gen-overlay.hidden {
  display: none;
}

/* Games overlay — full lesson area, iframe fills below toolbar */
.games-overlay {
  position: absolute;
  inset: 0;
  z-index: 105;
  display: flex;
  flex-direction: column;
  background: linear-gradient(160deg, #1e1b4b 0%, #312e81 40%, #4c1d95 100%);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg), 0 0 0 1px rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.12);
  overflow: hidden;
}
.games-overlay.hidden {
  display: none;
}

/* Below main nav (z-index 999 in app.css); fills rest of viewport */
.games-overlay.games-overlay--maximized {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  top: var(--games-max-top, 72px);
  width: auto;
  max-width: none;
  z-index: 500;
  border-radius: 0;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
}

.games-overlay.games-overlay--maximized .games-frame {
  border-radius: 0;
}

.games-overlay-inner {
  display: flex;
  flex-direction: column;
  flex: 1;
  min-height: 0;
  height: 100%;
}
.games-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 20px;
  background: linear-gradient(90deg, rgba(15, 23, 42, 0.85) 0%, rgba(30, 27, 75, 0.9) 100%);
  border-bottom: 1px solid rgba(255, 255, 255, 0.12);
  flex-shrink: 0;
}
.games-toolbar-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 8px;
  flex-shrink: 0;
}
.games-toolbar-icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 0;
  border: none;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.15);
  color: #f8fafc;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background 0.2s, transform 0.2s;
}
.games-toolbar-icon-btn:hover {
  background: rgba(255, 255, 255, 0.28);
  transform: scale(1.05);
}
.games-toolbar-text-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 40px;
  padding: 0 14px;
  border: none;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.15);
  color: #f8fafc;
  font-size: 0.88rem;
  font-weight: 600;
  font-family: var(--ls-font);
  cursor: pointer;
  transition: background 0.2s, transform 0.2s;
  white-space: nowrap;
}
.games-toolbar-text-btn:hover {
  background: rgba(255, 255, 255, 0.28);
  transform: translateY(-1px);
}
.games-toolbar-text-btn i {
  font-size: 0.9rem;
  opacity: 0.95;
}
.games-title {
  margin: 0;
  font-size: 1.15rem;
  font-weight: 700;
  color: #f8fafc;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  min-width: 0;
  flex: 1;
}
.games-title-emoji {
  font-size: 1.35rem;
  line-height: 1;
}
.games-subtitle {
  font-weight: 500;
  font-size: 0.88rem;
  color: rgba(248, 250, 252, 0.72);
}
.games-close {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border: none;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.15);
  color: #f8fafc;
  font-size: 1.15rem;
  cursor: pointer;
  transition: background 0.2s, transform 0.2s;
  flex-shrink: 0;
}
.games-close:hover {
  background: rgba(255, 255, 255, 0.28);
  transform: scale(1.05);
}
.games-frame-wrap {
  flex: 1;
  min-height: 0;
  position: relative;
  background: #0f172a;
}
.games-frame {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: none;
  border-radius: 0 0 var(--ls-radius-lg) var(--ls-radius-lg);
}

/* Phonics Track overlay — shares games-overlay layout, distinct theme */
.games-overlay.phonics-overlay {
  background: linear-gradient(160deg, #0c4a6e 0%, #0e7490 42%, #115e59 100%);
  border-color: rgba(255, 255, 255, 0.14);
}

.games-overlay.phonics-overlay .games-toolbar {
  background: linear-gradient(90deg, rgba(15, 23, 42, 0.9) 0%, rgba(8, 51, 68, 0.92) 100%);
  border-bottom-color: rgba(165, 243, 252, 0.15);
}

.games-overlay.phonics-overlay .games-title i {
  color: #67e8f9;
}

.games-overlay.phonics-overlay--maximized {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  top: var(--phonics-max-top, 72px);
  width: auto;
  max-width: none;
  z-index: 500;
  border-radius: 0;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
}

.games-overlay.phonics-overlay--maximized .games-frame {
  border-radius: 0;
}

.qgen-inner {
  display: flex;
  flex-direction: column;
  height: 100%;
}
.qgen-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: white;
}
.qgen-title {
  margin: 0;
  font-size: 1.15rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 8px;
}
.qgen-title i {
  font-size: 1.2rem;
}
.qgen-close {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: none;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  font-size: 1.1rem;
  cursor: pointer;
  transition: background 0.2s;
}
.qgen-close:hover {
  background: rgba(255, 255, 255, 0.35);
}
.qgen-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 40px 32px 32px;
  gap: 36px;
  overflow-y: auto;
  background: linear-gradient(165deg, #fffbeb 0%, #fef3c7 40%, #fde68a 100%);
}
.qgen-categories {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  justify-content: center;
}
.qgen-cat-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border: none;
  border-radius: 50px;
  font-family: var(--app-font);
  font-size: 1.05rem;
  font-weight: 700;
  color: white;
  cursor: pointer;
  transition: transform 0.25s cubic-bezier(0.4, 0, 0.2, 1),
              box-shadow 0.25s cubic-bezier(0.4, 0, 0.2, 1),
              filter 0.25s;
  letter-spacing: 0.01em;
}
.qgen-cat-btn:hover {
  transform: translateY(-3px) scale(1.04);
  filter: brightness(1.08);
}
.qgen-cat-btn:active {
  transform: translateY(0) scale(0.97);
}
.qgen-cat-btn[data-category="kids"] {
  background: linear-gradient(135deg, #38bdf8 0%, #0ea5e9 100%);
  box-shadow: 0 4px 16px rgba(56, 189, 248, 0.35);
}
.qgen-cat-btn[data-category="kids"]:hover {
  box-shadow: 0 8px 24px rgba(56, 189, 248, 0.45);
}
.qgen-cat-btn[data-category="kids"].active {
  box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.4), 0 8px 24px rgba(56, 189, 248, 0.45);
}
.qgen-cat-btn[data-category="adults"] {
  background: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
  box-shadow: 0 4px 16px rgba(59, 130, 246, 0.35);
}
.qgen-cat-btn[data-category="adults"]:hover {
  box-shadow: 0 8px 24px rgba(59, 130, 246, 0.45);
}
.qgen-cat-btn[data-category="adults"].active {
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.4), 0 8px 24px rgba(59, 130, 246, 0.45);
}
.qgen-cat-btn[data-category="ielts"] {
  background: linear-gradient(135deg, #06b6d4 0%, #0891b2 100%);
  box-shadow: 0 4px 16px rgba(6, 182, 212, 0.35);
}
.qgen-cat-btn[data-category="ielts"]:hover {
  box-shadow: 0 8px 24px rgba(6, 182, 212, 0.45);
}
.qgen-cat-btn[data-category="ielts"].active {
  box-shadow: 0 0 0 3px rgba(6, 182, 212, 0.4), 0 8px 24px rgba(6, 182, 212, 0.45);
}
.qgen-cat-btn[data-category="business"] {
  background: linear-gradient(135deg, #0ea5e9 0%, #0284c7 100%);
  box-shadow: 0 4px 16px rgba(14, 165, 233, 0.35);
}
.qgen-cat-btn[data-category="business"]:hover {
  box-shadow: 0 8px 24px rgba(14, 165, 233, 0.45);
}
.qgen-cat-btn[data-category="business"].active {
  box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.4), 0 8px 24px rgba(14, 165, 233, 0.45);
}
.qgen-display {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  max-width: 680px;
  min-height: 160px;
  padding: 32px 40px;
  background: white;
  border-radius: 20px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.06), 0 1px 4px rgba(0, 0, 0, 0.04);
  text-align: center;
}
.qgen-placeholder-text {
  font-size: 1.1rem;
  color: var(--app-text-muted);
  margin: 0;
  font-style: italic;
}
.qgen-question-text {
  font-size: 1.85rem;
  font-weight: 800;
  line-height: 1.35;
  color: var(--app-text);
  margin: 0;
  animation: qgenFadeIn 0.4s cubic-bezier(0.4, 0, 0.2, 1) both;
}
@keyframes qgenFadeIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}
.qgen-shuffle-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border: none;
  border-radius: 50px;
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: white;
  font-family: var(--app-font);
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.25s cubic-bezier(0.4, 0, 0.2, 1),
              box-shadow 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.3);
}
.qgen-shuffle-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(245, 158, 11, 0.45);
}
.qgen-shuffle-btn:active {
  transform: translateY(0) scale(0.97);
}
.qgen-shuffle-btn.hidden {
  display: none;
}
.qgen-shuffle-btn i {
  transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}
.qgen-shuffle-btn:hover i {
  transform: rotate(180deg);
}

@media (max-width: 600px) {
  .qgen-content {
    padding: 24px 16px 20px;
    gap: 24px;
  }
  .qgen-cat-btn {
    padding: 11px 22px;
    font-size: 0.95rem;
  }
  .qgen-question-text {
    font-size: 1.35rem;
  }
  .qgen-display {
    padding: 24px 20px;
    min-height: 120px;
  }
}

.whiteboard-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding: 12px 16px;
  background: linear-gradient(135deg, #0ea5e9 0%, #0284c7 100%);
  color: white;
}
.whiteboard-tools {
  display: flex;
  align-items: center;
  gap: 6px;
}
.wb-tool {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  padding: 0;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: background var(--ls-transition), transform var(--ls-transition);
}
.wb-tool:hover {
  background: rgba(255, 255, 255, 0.35);
}
.wb-tool.active {
  background: rgba(255, 255, 255, 0.95);
  color: #0284c7;
}
.whiteboard-colors {
  display: flex;
  align-items: center;
  gap: 6px;
}
.wb-color {
  width: 28px;
  height: 28px;
  padding: 0;
  border: 2px solid rgba(255, 255, 255, 0.5);
  border-radius: 50%;
  cursor: pointer;
  transition: border-color var(--ls-transition), transform var(--ls-transition);
}
.wb-color:hover {
  border-color: white;
  transform: scale(1.1);
}
.wb-color.active {
  border-color: white;
  border-width: 3px;
  box-shadow: 0 0 0 2px rgba(0, 0, 0, 0.2);
}
.whiteboard-thickness {
  display: flex;
  align-items: center;
  gap: 4px;
}
.wb-thick {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  padding: 0;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: background var(--ls-transition);
}
.wb-thick:hover {
  background: rgba(255, 255, 255, 0.35);
}
.wb-thick.active {
  background: rgba(255, 255, 255, 0.95);
  color: #0284c7;
}
.wb-thick-line {
  display: block;
  background: currentColor;
  border-radius: 2px;
}
.wb-thick-line.wb-thin {
  width: 16px;
  height: 2px;
}
.wb-thick-line.wb-thick {
  width: 16px;
  height: 5px;
}
.whiteboard-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}
.wb-action {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  font-size: 0.9rem;
  font-weight: 600;
  font-family: var(--ls-font);
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: background var(--ls-transition);
}
.wb-action:hover {
  background: rgba(255, 255, 255, 0.35);
}
.wb-close {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  padding: 0;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: background var(--ls-transition);
}
.wb-close:hover {
  background: rgba(220, 38, 38, 0.8);
}
.whiteboard-canvas-wrap {
  position: relative;
  flex: 1;
  min-height: 400px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
  overflow: hidden;
}
#whiteboardCanvas {
  max-width: 100%;
  max-height: 100%;
  border-radius: var(--ls-radius);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  cursor: crosshair;
  touch-action: none;
}
.wb-drag-ghost {
  position: fixed;
  pointer-events: none;
  z-index: 1000;
  background-size: contain;
  background-repeat: no-repeat;
  opacity: 0.9;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
  border-radius: 4px;
}
.wb-drag-ghost.hidden {
  display: none !important;
}
.whiteboard-text-size {
  display: flex;
  align-items: center;
  gap: 4px;
}
.wb-text-size {
  width: 32px;
  height: 32px;
  padding: 0;
  font-size: 0.8rem;
  font-weight: 700;
  font-family: var(--ls-font);
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: background var(--ls-transition);
}
.wb-text-size:hover {
  background: rgba(255, 255, 255, 0.35);
}
.wb-text-size.active {
  background: rgba(255, 255, 255, 0.95);
  color: #0284c7;
}

/* Whiteboard text modal */
.wb-text-modal {
  position: absolute;
  inset: 0;
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.wb-text-modal.hidden {
  display: none !important;
}

.wb-text-modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(15, 23, 42, 0.5);
  backdrop-filter: blur(4px);
  animation: wbTextBackdropIn 0.25s ease;
}

@keyframes wbTextBackdropIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.wb-text-modal-dialog {
  position: relative;
  width: 100%;
  max-width: 420px;
  background: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
  border-radius: 16px;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25), 0 0 0 1px rgba(0, 0, 0, 0.05);
  overflow: hidden;
  animation: wbTextDialogIn 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes wbTextDialogIn {
  from {
    opacity: 0;
    transform: scale(0.95) translateY(-10px);
  }
  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

.wb-text-modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  background: linear-gradient(135deg, #0ea5e9 0%, #0284c7 100%);
  color: white;
}

.wb-text-modal-header h3 {
  margin: 0;
  font-size: 1.25rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 10px;
}

.wb-text-modal-close {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  transition: background 0.2s;
}

.wb-text-modal-close:hover {
  background: rgba(255, 255, 255, 0.35);
}

.wb-text-modal-body {
  padding: 24px;
}

.wb-text-modal-body label {
  display: block;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--ls-text);
  margin-bottom: 10px;
}

.wb-text-modal-body textarea {
  width: 100%;
  padding: 14px 16px;
  font-size: 1rem;
  font-family: var(--ls-font);
  line-height: 1.5;
  color: var(--ls-text);
  background: #fff;
  border: 2px solid var(--ls-border);
  border-radius: 10px;
  resize: vertical;
  min-height: 80px;
  transition: border-color 0.2s, box-shadow 0.2s;
  box-sizing: border-box;
}

.wb-text-modal-body textarea:focus {
  outline: none;
  border-color: #0284c7;
  box-shadow: 0 0 0 3px rgba(2, 132, 199, 0.2);
}

.wb-text-modal-body textarea::placeholder {
  color: #94a3b8;
}

.wb-text-modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  padding: 16px 24px;
  background: #f8fafc;
  border-top: 1px solid var(--ls-border);
}

.wb-text-modal-btn {
  padding: 12px 24px;
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--ls-font);
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.wb-text-modal-cancel {
  background: #e2e8f0;
  color: #475569;
}

.wb-text-modal-cancel:hover {
  background: #cbd5e1;
}

.wb-text-modal-add {
  background: linear-gradient(135deg, #0ea5e9 0%, #0284c7 100%);
  color: white;
  box-shadow: 0 4px 14px rgba(2, 132, 199, 0.4);
}

.wb-text-modal-add:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(2, 132, 199, 0.45);
}

.video-overlay-inner {
  display: flex;
  flex-direction: column;
  flex: 1;
  min-height: 0;
  overflow: hidden;
}
.video-overlay-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  background: linear-gradient(135deg, #7c3aed 0%, #6d28d9 100%);
  color: white;
}
.video-overlay-title {
  margin: 0;
  font-size: 1.1rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
}
.btn-video-close {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
}
.btn-video-close:hover {
  background: rgba(255, 255, 255, 0.3);
}
.video-library-view {
  flex: 1;
  overflow-y: auto;
  padding: 20px;
}
.video-add-form {
  display: flex;
  gap: 12px;
  margin-bottom: 24px;
  flex-wrap: wrap;
}
.video-url-input {
  flex: 1;
  min-width: 200px;
  padding: 10px 16px;
  font-size: 0.95rem;
  font-family: var(--ls-font);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  background: var(--ls-surface);
}
.video-url-input:focus {
  outline: 2px solid #7c3aed;
  outline-offset: 0;
}
.btn-add-video {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  font-family: var(--ls-font);
  color: white;
  background: linear-gradient(135deg, #7c3aed 0%, #6d28d9 100%);
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
}
.btn-add-video:hover {
  opacity: 0.95;
}
.video-thumbnails {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 20px;
}
.video-thumb-card {
  position: relative;
  cursor: pointer;
  border-radius: var(--ls-radius-lg);
  overflow: hidden;
  background: var(--ls-bg);
  border: 1px solid var(--ls-border);
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}
.video-thumb-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--ls-shadow-lg);
}
.video-thumb-img-wrap {
  position: relative;
  aspect-ratio: 16/9;
  background: #1e293b;
}
.video-thumb-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.video-thumb-play {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, 0.4);
  color: white;
  font-size: 2.5rem;
  opacity: 0.9;
}
.video-thumb-card:hover .video-thumb-play {
  background: rgba(124, 58, 237, 0.6);
}
.video-thumb-title {
  display: block;
  padding: 12px 44px 12px 12px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--ls-text);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.btn-video-remove {
  position: absolute;
  top: 8px;
  right: 8px;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  color: rgba(255, 255, 255, 0.9);
  background: rgba(0, 0, 0, 0.5);
  border: none;
  border-radius: 6px;
  cursor: pointer;
  z-index: 2;
  transition: background var(--ls-transition);
}
.btn-video-remove:hover {
  background: rgba(220, 38, 38, 0.9);
}
.video-empty-state {
  text-align: center;
  padding: 48px 24px;
  color: var(--ls-text-muted);
}
.video-empty-state i {
  font-size: 3rem;
  margin-bottom: 16px;
  opacity: 0.5;
}
.video-empty-state.hidden {
  display: none;
}
.video-player-view {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
}
.video-player-view.hidden {
  display: none;
}
.video-player-wrap {
  flex: 1;
  min-height: 400px;
  padding: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #000;
}
.video-player-frame {
  width: 100%;
  max-width: 900px;
  aspect-ratio: 16/9;
  border: none;
}
.btn-back-to-library {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 20px 20px;
  padding: 10px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  font-family: var(--ls-font);
  color: #7c3aed;
  background: transparent;
  border: 2px solid #7c3aed;
  border-radius: var(--ls-radius);
  cursor: pointer;
  align-self: flex-start;
}
.btn-back-to-library:hover {
  background: rgba(124, 58, 237, 0.1);
}

/* PDF overlay - below header so stars remain visible */
.pdf-overlay {
  position: fixed;
  top: 80px;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1001;
  display: flex;
  flex-direction: column;
  background: var(--ls-surface);
  box-shadow: var(--ls-shadow-lg);
  overflow: hidden;
}
.pdf-overlay.hidden {
  display: none;
}
.pdf-overlay-inner {
  display: flex;
  flex-direction: column;
  flex: 1;
  min-height: 0;
  overflow: hidden;
}
.pdf-overlay-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  background: linear-gradient(135deg, #dc2626 0%, #b91c1c 100%);
  color: white;
  gap: 16px;
  flex-shrink: 0;
}
.pdf-toolbar-zoom {
  display: flex;
  align-items: center;
  gap: 10px;
}
.pdf-toolbar-zoom.hidden {
  display: none !important;
}
.pdf-toolbar-zoom .btn-pdf-zoom-out,
.pdf-toolbar-zoom .btn-pdf-zoom-in {
  width: 36px;
  height: 36px;
  padding: 0;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: 1px solid rgba(255, 255, 255, 0.4);
  border-radius: var(--ls-radius);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background var(--ls-transition);
}
.pdf-toolbar-zoom .btn-pdf-zoom-out:hover,
.pdf-toolbar-zoom .btn-pdf-zoom-in:hover {
  background: rgba(255, 255, 255, 0.35);
}
.pdf-toolbar-zoom .pdf-zoom-level {
  font-size: 0.9rem;
  font-weight: 600;
  color: white;
  min-width: 44px;
  text-align: center;
}
.pdf-overlay-title {
  margin: 0;
  font-size: 1.1rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
}
.pdf-beta-badge {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 2px 8px;
  background: rgba(255, 255, 255, 0.3);
  border-radius: 4px;
  margin-left: 4px;
}
.pdf-beta-note {
  margin-bottom: 12px !important;
}
.pdf-beta-note i {
  margin-right: 4px;
}
.btn-pdf-close {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
}
.btn-pdf-close:hover {
  background: rgba(255, 255, 255, 0.3);
}
.pdf-library-view {
  flex: 1;
  overflow-y: auto;
  padding: 20px;
}
.pdf-upload-section {
  margin-bottom: 24px;
}
.pdf-upload-notes {
  background: #fef2f2;
  border: 1px solid #fecaca;
  border-radius: var(--ls-radius);
  padding: 16px;
  margin-bottom: 16px;
  font-size: 0.9rem;
  color: var(--ls-text);
}
.pdf-upload-notes p {
  margin: 0 0 8px;
}
.pdf-upload-notes p:last-child {
  margin-bottom: 0;
}
.pdf-upload-notes a {
  color: #dc2626;
  font-weight: 600;
}
.pdf-upload-notes a:hover {
  text-decoration: underline;
}
.pdf-add-form {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  align-items: center;
}
.pdf-title-input {
  flex: 1;
  min-width: 180px;
  padding: 10px 16px;
  font-size: 0.95rem;
  font-family: var(--ls-font);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  background: var(--ls-surface);
}
.pdf-title-input:focus {
  outline: 2px solid #dc2626;
  outline-offset: 0;
}
.btn-pdf-upload-label {
  cursor: pointer;
  margin: 0;
}
.btn-pdf-upload {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  font-family: var(--ls-font);
  color: #dc2626;
  background: transparent;
  border: 2px solid #dc2626;
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: background var(--ls-transition), color var(--ls-transition);
}
.btn-pdf-upload:hover {
  background: rgba(220, 38, 38, 0.1);
}
.btn-add-pdf {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  font-family: var(--ls-font);
  color: white;
  background: linear-gradient(135deg, #dc2626 0%, #b91c1c 100%);
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
}
.btn-add-pdf:hover:not(:disabled) {
  opacity: 0.95;
}
.btn-add-pdf:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}
.pdf-limit-hint {
  margin: 8px 0 0;
  font-size: 0.85rem;
  color: var(--ls-text-muted);
}
.pdf-thumbnails {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 20px;
}
.pdf-thumb-card {
  position: relative;
  cursor: pointer;
  border-radius: var(--ls-radius-lg);
  overflow: hidden;
  background: var(--ls-bg);
  border: 1px solid var(--ls-border);
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}
.pdf-thumb-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--ls-shadow-lg);
}
.pdf-thumb-icon-wrap {
  aspect-ratio: 3/4;
  background: linear-gradient(145deg, #fef2f2 0%, #fee2e2 100%);
  display: flex;
  align-items: center;
  justify-content: center;
}
.pdf-thumb-icon {
  font-size: 3.5rem;
  color: #dc2626;
  opacity: 0.9;
}
.pdf-thumb-title {
  display: block;
  padding: 12px 44px 12px 12px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--ls-text);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.btn-pdf-remove {
  position: absolute;
  top: 8px;
  right: 8px;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  color: rgba(255, 255, 255, 0.9);
  background: rgba(0, 0, 0, 0.5);
  border: none;
  border-radius: 6px;
  cursor: pointer;
  z-index: 2;
  transition: background var(--ls-transition);
}
.btn-pdf-remove:hover {
  background: rgba(220, 38, 38, 0.9);
}
.pdf-empty-state {
  text-align: center;
  padding: 48px 24px;
  color: var(--ls-text-muted);
}
.pdf-empty-state i {
  font-size: 3rem;
  margin-bottom: 16px;
  opacity: 0.5;
}
.pdf-empty-state.hidden {
  display: none;
}
.pdf-viewer-view {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
}
.pdf-viewer-view.hidden {
  display: none;
}
.pdf-viewer-wrap {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
  padding: 12px;
  background: var(--ls-bg);
}
.pdf-viewer-box {
  flex: 1;
  min-height: 0;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--ls-surface);
  border-radius: var(--ls-radius);
  border: 1px solid var(--ls-border);
  box-shadow: var(--ls-shadow);
}
.pdf-viewer-scalable {
  width: 100%;
  height: 100%;
  min-height: 500px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.pdf-viewer-frame {
  width: 100%;
  height: 100%;
  min-height: 500px;
  border: none;
  border-radius: var(--ls-radius);
  background: white;
  display: block;
}
.btn-back-to-pdf-library {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 20px 20px;
  padding: 10px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  font-family: var(--ls-font);
  color: #dc2626;
  background: transparent;
  border: 2px solid #dc2626;
  border-radius: var(--ls-radius);
  cursor: pointer;
  align-self: flex-start;
}
.btn-back-to-pdf-library:hover {
  background: rgba(220, 38, 38, 0.1);
}

/* Link library overlay - browser style with URL bar */
.link-overlay {
  position: absolute;
  inset: 0;
  z-index: 100;
  display: flex;
  flex-direction: column;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg);
  border: 1px solid var(--ls-border);
  overflow: hidden;
}
.link-overlay.hidden {
  display: none;
}
.link-overlay-inner {
  position: relative;
  display: flex;
  flex-direction: column;
  flex: 1;
  min-height: 0;
  overflow: hidden;
}
.link-browser-toolbar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 16px;
  background: var(--ls-bg);
  border-bottom: 1px solid var(--ls-border);
}
.link-url-input {
  flex: 1;
  padding: 10px 16px;
  font-size: 0.95rem;
  font-family: var(--ls-font);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  background: var(--ls-surface);
}
.link-url-input:focus {
  outline: 2px solid var(--ls-primary);
  outline-offset: 0;
}
.btn-link-go {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: var(--ls-primary);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
}
.btn-link-go:hover {
  background: var(--ls-primary-dark);
}
.btn-link-info {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: transparent;
  color: var(--ls-text-muted);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  cursor: pointer;
}
.btn-link-info:hover {
  background: var(--ls-bg);
  color: var(--ls-primary);
}
.btn-link-add {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 0 16px;
  height: 40px;
  font-size: 0.9rem;
  font-weight: 600;
  font-family: var(--ls-font);
  background: var(--ls-primary);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
}
.btn-link-add:hover {
  background: var(--ls-primary-dark);
}
.btn-link-toggle-saved {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 0 14px;
  height: 40px;
  font-size: 0.85rem;
  font-weight: 500;
  font-family: var(--ls-font);
  background: var(--ls-bg);
  color: var(--ls-text);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  cursor: pointer;
}
.btn-link-toggle-saved:hover {
  background: var(--ls-border);
}
.btn-link-close {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: var(--ls-text-muted);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
}
.btn-link-close:hover {
  background: var(--ls-text);
}
.link-browser-info-popup {
  position: absolute;
  top: 60px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 110;
  max-width: 380px;
  padding: 20px 24px;
  background: var(--ls-surface);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-lg);
  box-shadow: var(--ls-shadow-lg);
}
.link-browser-info-popup.hidden {
  display: none;
}
.link-browser-info-content {
  position: relative;
}
.link-browser-info-close {
  position: absolute;
  top: -8px;
  right: -8px;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--ls-bg);
  border: 1px solid var(--ls-border);
  border-radius: 50%;
  color: var(--ls-text-muted);
  cursor: pointer;
}
.link-browser-info-close:hover {
  color: var(--ls-text);
}
.link-browser-info-content h4 {
  margin: 0 0 12px;
  font-size: 1rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--ls-text);
}
.link-browser-info-content h4 i {
  color: var(--ls-primary);
}
.link-browser-info-content p {
  margin: 0 0 10px;
  font-size: 0.9rem;
  line-height: 1.5;
  color: var(--ls-text);
}
.link-browser-info-content p:last-child {
  margin-bottom: 0;
}

.link-saved-strip {
  padding: 14px 16px;
  background: var(--ls-surface);
  border-bottom: 1px solid var(--ls-border);
  overflow-x: auto;
}
.link-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}
.link-chip {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  min-width: 200px;
  max-width: 320px;
  font-size: 0.9rem;
  font-family: var(--ls-font);
  background: var(--ls-bg);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-lg);
  color: var(--ls-text);
  cursor: pointer;
  text-align: left;
  transition: background var(--ls-transition), border-color var(--ls-transition);
}
.link-chip:hover {
  background: rgba(13, 148, 136, 0.08);
  border-color: var(--ls-primary);
}
.link-chip-favicon,
.link-chip-fallback {
  width: 36px;
  height: 36px;
  min-width: 36px;
  min-height: 36px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}
.link-chip-favicon {
  width: 36px;
  height: 36px;
  object-fit: contain;
}
.link-chip-fallback {
  display: none;
  color: var(--ls-primary);
  font-size: 1.25rem;
}
.link-chip-name {
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.link-chip-delete {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4px 6px;
  margin: -2px 0 -2px 4px;
  color: var(--ls-text-muted);
  opacity: 0.85;
  border-radius: 4px;
}
.link-chip-delete:hover {
  background: rgba(220, 38, 38, 0.15);
  color: #dc2626;
  opacity: 1;
}
.link-browser-frame-wrap {
  flex: 1;
  min-height: 400px;
  position: relative;
}
.link-browser-frame {
  width: 100%;
  height: 100%;
  min-height: 400px;
  border: none;
}
.link-browser-blocked {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  background: var(--ls-bg);
  color: var(--ls-text-muted);
}
.link-browser-blocked.hidden {
  display: none;
}
.link-browser-blocked i {
  font-size: 3rem;
  opacity: 0.5;
}

.lesson-viewer {
  position: relative;
  min-height: 480px;
  border-radius: var(--ls-radius-xl);
  overflow: hidden;
  background: var(--ls-surface);
  padding-bottom: 72px;
  box-shadow: var(--ls-shadow-lg);
  border: 1px solid var(--ls-border);
}

.lesson-placeholder {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 480px;
  padding: 60px 24px;
  background: linear-gradient(165deg, #f0fdfa 0%, #ccfbf1 40%, #99f6e4 100%);
  background-size: 200% 200%;
  animation: gradientShift 8s ease infinite;
}

@keyframes gradientShift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

.lesson-placeholder-icon {
  width: 120px;
  height: 120px;
  margin-bottom: 24px;
  opacity: 0.9;
}

.lesson-placeholder h2 {
  margin: 0 0 8px;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--ls-text);
}

.lesson-placeholder p {
  margin: 0 0 28px;
  font-size: 1rem;
  color: var(--ls-text-muted);
}

.lesson-placeholder .choose-lesson-button {
  font-size: 1rem;
  padding: 16px 32px;
}

.lesson-embed {
  padding: 24px;
  min-height: 480px;
  border-radius: var(--ls-radius-xl);
  background: var(--ls-surface);
  transition: opacity 0.3s ease;
}

.lesson-embed iframe {
  border-radius: var(--ls-radius);
  border: none;
}

@media (prefers-reduced-motion: reduce) {
  .lesson-placeholder {
    animation: none;
    background: #f0fdfa;
  }
}

.navbar-inner {
  display: flex;
  flex-wrap: nowrap;
  align-items: center;
  justify-content: space-between;
  gap: clamp(8px, 1.2vw, 16px);
}

.nav-left {
  display: flex;
  align-items: center;
  gap: clamp(6px, 1vw, 20px);
  flex-shrink: 1;
  min-width: 0;
}

.nav-right {
  display: flex;
  align-items: center;
  gap: clamp(8px, 1vw, 16px);
  flex-shrink: 1;
  min-width: 0;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.student-selector {
  position: relative;
}

.student-selector-trigger {
  display: flex;
  align-items: center;
  gap: clamp(6px, 0.8vw, 12px);
  padding: clamp(4px, 0.6vw, 8px) clamp(8px, 1vw, 14px);
  min-width: 0;
  min-height: clamp(36px, 3.2vw, var(--ls-touch-min));
  background: var(--ls-surface);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-lg);
  cursor: pointer;
  transition: border-color var(--ls-transition), box-shadow var(--ls-transition);
  font-family: var(--ls-font);
}

.student-selector-trigger:hover {
  border-color: var(--ls-primary);
  box-shadow: 0 0 0 3px rgba(13, 148, 136, 0.1);
}

.student-selector-trigger:focus-visible {
  outline: 2px solid var(--ls-primary);
  outline-offset: 2px;
}

.student-avatar {
  width: clamp(28px, 2.6vw, 36px);
  height: clamp(28px, 2.6vw, 36px);
  min-width: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  border-radius: 50%;
  font-size: clamp(0.65rem, 0.8vw, 0.75rem);
  flex-shrink: 0;
  font-weight: 700;
}

.student-avatar i {
  font-size: 0.9rem;
}
.student-avatar.has-img {
  padding: 0;
  background: var(--ls-surface);
}
.student-avatar.has-img img {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
}

.student-info {
  flex: 1;
  min-width: 0;
  text-align: left;
}

.student-name {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--ls-text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.student-stars {
  display: block;
  font-size: 0.75rem;
  color: var(--ls-text-muted);
}

.student-profile-btn {
  width: 36px;
  height: 36px;
  min-width: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(13, 148, 136, 0.1);
  border: none;
  color: var(--ls-primary);
  border-radius: var(--ls-radius);
  cursor: pointer;
  font-size: 1rem;
  transition: background var(--ls-transition), color var(--ls-transition);
}

.student-profile-btn:hover {
  background: rgba(13, 148, 136, 0.2);
  color: var(--ls-primary-dark);
}

.student-profile-btn:focus-visible {
  outline: 2px solid var(--ls-primary);
  outline-offset: 2px;
}

.student-chevron {
  font-size: 0.7rem;
  color: var(--ls-text-muted);
  transition: transform var(--ls-transition);
}

.student-selector-trigger[aria-expanded="true"] .student-chevron {
  transform: rotate(180deg);
}

.student-dropdown {
  display: none;
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  min-width: 260px;
  max-width: 320px;
  max-height: 320px;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-lg);
  box-shadow: var(--ls-shadow-lg);
  border: 1px solid var(--ls-border);
  overflow: hidden;
  z-index: 1100;
  animation: viewFadeIn 0.2s ease-out;
}

.student-dropdown.show {
  display: block;
}

.student-list {
  overflow-y: auto;
  max-height: 240px;
  padding: var(--ls-spacing-sm);
}

.student-list-empty,
.student-list-error {
  padding: var(--ls-spacing-lg);
  text-align: center;
  color: var(--ls-text-muted);
  font-size: 0.9rem;
  margin: 0;
}

.student-list-item {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
  padding: 12px var(--ls-spacing-md);
  border: none;
  background: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  font-family: var(--ls-font);
  text-align: left;
  transition: background var(--ls-transition);
  min-height: var(--ls-touch-min);
}

.student-list-item:hover {
  background: var(--ls-bg);
}

.student-item-avatar {
  width: 36px;
  height: 36px;
  min-width: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--ls-primary-light) 0%, var(--ls-primary) 100%);
  color: white;
  border-radius: 50%;
  font-size: 0.75rem;
  font-weight: 700;
  overflow: hidden;
}
.student-item-avatar.has-img {
  padding: 0;
  background: var(--ls-surface);
}
.student-item-avatar.has-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

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

.student-item-name {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--ls-text);
}

.student-item-stars {
  display: block;
  font-size: 0.75rem;
  color: var(--ls-accent);
}

.student-item-stars i {
  font-size: 0.65rem;
}

.student-item-profile-icon {
  width: 36px;
  height: 36px;
  min-width: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ls-primary);
  border-radius: var(--ls-radius);
  cursor: pointer;
  font-size: 0.9rem;
  transition: background var(--ls-transition), color var(--ls-transition);
  flex-shrink: 0;
}

.student-item-profile-icon:hover {
  background: rgba(13, 148, 136, 0.1);
  color: var(--ls-primary-dark);
}

.student-dropdown-add {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 14px var(--ls-spacing-lg);
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  border: none;
  font-family: var(--ls-font);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: background var(--ls-transition);
  border-top: 1px solid var(--ls-border);
}

.student-dropdown-add:hover {
  background: linear-gradient(135deg, var(--ls-primary-light) 0%, var(--ls-primary) 100%);
  color: white;
}

.student-dropdown-add:focus-visible {
  outline: 2px solid var(--ls-primary);
  outline-offset: -2px;
}

/* Star award bar */
.star-award-bar {
  display: flex;
  align-items: center;
  gap: clamp(6px, 1vw, 14px);
  flex-wrap: nowrap;
  flex-shrink: 1;
  min-width: 0;
  padding: clamp(4px, 0.6vw, 8px) clamp(8px, 1vw, 16px);
  background: linear-gradient(135deg, rgba(251, 191, 36, 0.12) 0%, rgba(245, 158, 11, 0.08) 100%);
  border-radius: var(--ls-radius-lg);
  border: 1px solid rgba(245, 158, 11, 0.25);
  box-shadow: 0 2px 8px rgba(245, 158, 11, 0.1);
}

.star-slots {
  display: flex;
  gap: clamp(2px, 0.4vw, 6px);
  align-items: center;
  flex-shrink: 1;
  min-width: 0;
}

.star-slot {
  width: clamp(26px, 2.8vw, 38px);
  height: clamp(26px, 2.8vw, 38px);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: clamp(0.9rem, 1vw, 1.35rem);
  color: var(--ls-border);
  border-radius: 8px;
  flex-shrink: 1;
  transition: all var(--ls-transition);
}

.star-slot::before {
  font-family: 'Font Awesome 6 Free';
  content: '\f005';
  font-weight: 400;
}

.star-slot.filled.star-mode {
  color: #f59e0b;
}

.star-slot.filled.star-mode::before {
  font-weight: 900;
}

.star-session-badge {
  font-size: clamp(0.7rem, 0.9vw, 0.95rem);
  font-weight: 700;
  color: var(--ls-text);
  background: rgba(255, 255, 255, 0.9);
  padding: clamp(3px, 0.4vw, 6px) clamp(8px, 1vw, 14px);
  border-radius: 20px;
  min-width: 0;
  white-space: nowrap;
  text-align: center;
  flex-shrink: 1;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06);
}

.btn-award-star {
  width: clamp(32px, 3.2vw, var(--ls-touch-min));
  height: clamp(32px, 3.2vw, var(--ls-touch-min));
  min-width: 32px;
  min-height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #fbbf24 0%, #f59e0b 100%);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  font-size: clamp(0.9rem, 1vw, 1.25rem);
  flex-shrink: 0;
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.4);
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}

.btn-award-star:hover {
  transform: scale(1.08);
  box-shadow: 0 6px 20px rgba(245, 158, 11, 0.5);
}

.btn-award-star .award-icon {
  color: white;
}

.btn-award-star:focus-visible {
  outline: 2px solid var(--ls-accent);
  outline-offset: 2px;
}

/* Timer */
.timer-wrap {
  position: relative;
}

.btn-timer {
  width: clamp(32px, 3.2vw, var(--ls-touch-min));
  height: clamp(32px, 3.2vw, var(--ls-touch-min));
  min-width: 32px;
  min-height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  color: var(--ls-primary);
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  font-size: clamp(0.9rem, 1vw, 1.25rem);
  flex-shrink: 0;
  transition: background var(--ls-transition), color var(--ls-transition);
}

.btn-timer:hover {
  background: rgba(13, 148, 136, 0.1);
  color: var(--ls-primary-dark);
}

.btn-timer.hidden {
  display: none;
}

.timer-display {
  display: none;
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.1rem, 1.3vw, 1.75rem);
  font-weight: 700;
  color: var(--ls-primary);
  min-width: 0;
  white-space: nowrap;
  text-align: center;
  padding: clamp(3px, 0.4vw, 6px) clamp(8px, 1vw, 16px);
  background: linear-gradient(135deg, rgba(13, 148, 136, 0.12) 0%, rgba(20, 184, 166, 0.08) 100%);
  border-radius: var(--ls-radius);
  border: 1px solid rgba(13, 148, 136, 0.25);
  flex-shrink: 1;
}

.timer-display.show {
  display: flex;
  align-items: center;
  justify-content: center;
}

.timer-modal {
  display: none;
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: 1100;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-lg);
  box-shadow: var(--ls-shadow-lg);
  border: 1px solid var(--ls-border);
  padding: var(--ls-spacing-lg);
  min-width: 240px;
}

.timer-modal.show {
  display: block;
  animation: viewFadeIn 0.2s ease-out;
}

.timer-modal-content h4 {
  margin: 0 0 8px;
  font-size: 1rem;
  display: flex;
  align-items: center;
  gap: 8px;
}

.timer-modal-content h4 i {
  color: var(--ls-primary);
}

.timer-modal-hint {
  margin: 0 0 12px;
  font-size: 0.85rem;
  color: var(--ls-text-muted);
}

.timer-modal-content input {
  width: 100%;
  padding: 12px 16px;
  margin-bottom: 16px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  font-size: 1.1rem;
  font-family: var(--ls-font);
}

.timer-modal-content input:focus {
  outline: none;
  border-color: var(--ls-primary);
}

.timer-modal-actions {
  display: flex;
  gap: 10px;
  justify-content: flex-end;
}

/* Timer ended modal */
.timer-ended-modal .modal-dialog {
  max-width: 360px;
}

.timer-ended-body {
  text-align: center;
  padding: var(--ls-spacing-xl);
}

.timer-ended-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  border-radius: 50%;
  font-size: 1.75rem;
}

.timer-ended-body h3 {
  margin: 0 0 20px;
  font-size: 1.25rem;
  color: var(--ls-text);
}

.timer-ended-ok {
  padding: 12px 32px;
}

/* Mobile warning modal */
.mobile-warning-modal .modal-dialog {
  max-width: 400px;
}

.mobile-warning-body {
  text-align: center;
  padding: var(--ls-spacing-xl);
}

.mobile-warning-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--app-accent) 0%, var(--app-accent-light) 100%);
  color: white;
  border-radius: 50%;
  font-size: 1.75rem;
}

.mobile-warning-text {
  margin: 0 0 20px;
  font-size: 1rem;
  line-height: 1.5;
  color: var(--ls-text);
}

.mobile-warning-ok {
  padding: 12px 32px;
}

.switch {
  position: relative;
  display: inline-block;
  width: 60px;
  height: 34px;
}

.switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: #ccc;
  transition: 0.4s;
  border-radius: 34px;
}

.slider:before {
  position: absolute;
  content: "";
  height: 26px;
  width: 26px;
  left: 4px;
  bottom: 4px;
  background-color: white;
  transition: 0.4s;
  border-radius: 50%;
}

input:checked + .slider {
  background-color: #31d61f;
}

input:checked + .slider:before {
  transform: translateX(26px);
}

/* Profile dropdown */
.profile-trigger-wrap {
  position: relative;
}

.btn-profile {
  width: clamp(32px, 3.2vw, var(--ls-touch-min));
  height: clamp(32px, 3.2vw, var(--ls-touch-min));
  min-width: 32px;
  min-height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  color: var(--ls-primary);
  cursor: pointer;
  font-size: clamp(1.1rem, 1.2vw, 1.5rem);
  border-radius: 50%;
  flex-shrink: 0;
  transition: background var(--ls-transition), color var(--ls-transition);
}

.btn-profile:hover {
  background: rgba(13, 148, 136, 0.1);
  color: var(--ls-primary-dark);
}

.btn-profile:focus-visible {
  outline: 2px solid var(--ls-primary);
  outline-offset: 2px;
}

.btn-profile-avatar {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  overflow: hidden;
  font-size: 1.5rem;
  color: var(--ls-primary);
}

.btn-profile-avatar.has-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.profile-dropdown-header {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: var(--ls-spacing-md);
  border-bottom: 1px solid var(--ls-border);
  margin-bottom: var(--ls-spacing-sm);
}

.profile-dropdown-avatar-wrap {
  margin-bottom: 8px;
}

.profile-dropdown-avatar {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--ls-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--ls-text-muted);
  overflow: hidden;
}

.profile-dropdown-avatar.has-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.profile-dropdown-item[for] {
  cursor: pointer;
}

.profile-dropdown {
  display: none;
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 260px;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-lg);
  box-shadow: var(--ls-shadow-lg);
  border: 1px solid var(--ls-border);
  padding: var(--ls-spacing-sm);
  z-index: 1100;
  font-family: var(--ls-font);
}

.profile-dropdown.show {
  display: block;
  animation: viewFadeIn 0.2s ease-out;
}

.profile-name {
  display: block;
  font-weight: 600;
  color: var(--ls-text);
  font-size: 0.95rem;
}

.profile-email {
  display: block;
  font-size: 0.85rem;
  color: var(--ls-text-muted);
  margin-top: 2px;
}

.profile-dropdown-item {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  padding: 12px var(--ls-spacing-md);
  border: none;
  background: none;
  color: var(--ls-text);
  font-size: 0.9rem;
  font-family: var(--ls-font);
  cursor: pointer;
  border-radius: var(--ls-radius);
  text-decoration: none;
  transition: background var(--ls-transition);
  text-align: left;
}

.profile-dropdown-item:hover {
  background: var(--ls-bg);
}

.profile-dropdown-logout {
  color: #dc2626;
}

.profile-dropdown-logout:hover {
  background: #fef2f2;
}

/* Trial banner in profile */
.profile-trial-banner {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px var(--ls-spacing-md);
  margin: 0 0 var(--ls-spacing-sm);
  background: linear-gradient(135deg, rgba(245, 158, 11, 0.12) 0%, rgba(251, 191, 36, 0.08) 100%);
  border-radius: var(--ls-radius);
  font-size: 0.85rem;
  color: var(--ls-text);
  border: 1px solid rgba(245, 158, 11, 0.25);
}

.profile-trial-banner i {
  color: var(--app-accent);
  flex-shrink: 0;
}

.profile-trial-banner.hidden {
  display: none !important;
}

/* Upgrade button */
.profile-upgrade-btn {
  background: linear-gradient(135deg, var(--app-primary) 0%, var(--app-primary-dark) 100%) !important;
  color: white !important;
  font-weight: 600;
  justify-content: center;
  margin-bottom: 4px;
}

.profile-upgrade-btn:hover {
  background: linear-gradient(135deg, var(--app-primary-light) 0%, var(--app-primary) 100%) !important;
  color: white !important;
}

/* Profile dropdown divider & OTC apps section */
.profile-dropdown-divider {
  height: 1px;
  background: var(--ls-border);
  margin: var(--ls-spacing-sm) 0;
}

.profile-dropdown-section {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding-top: var(--ls-spacing-sm);
}

.profile-dropdown-section-title {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--ls-text-muted);
  padding: 0 var(--ls-spacing-md) 8px;
  margin-bottom: 4px;
  border-bottom: 1px solid var(--ls-border);
}

.profile-otc-app {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px var(--ls-spacing-md);
  color: var(--ls-text);
  font-size: 0.88rem;
  text-decoration: none;
  border-radius: var(--ls-radius);
  transition: background var(--ls-transition), color var(--ls-transition);
}

.profile-otc-app:hover {
  background: var(--ls-bg);
  color: var(--app-primary);
}

.profile-otc-app i {
  width: 18px;
  flex-shrink: 0;
  opacity: 0.8;
}

/* Profile pricing modal */
.profile-pricing-modal .modal-dialog {
  max-width: 620px;
  width: 100%;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.2);
  overflow: hidden;
}

.profile-pricing-modal .modal-content {
  display: flex;
  flex-direction: column;
}

.profile-pricing-modal .modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 24px 28px;
  background: linear-gradient(135deg, var(--app-primary) 0%, var(--app-primary-dark) 100%);
  color: white;
}

.profile-pricing-modal .modal-title {
  margin: 0;
  font-size: 1.35rem;
  font-weight: 700;
}

.profile-pricing-modal .modal-title i {
  margin-right: 8px;
  opacity: 0.95;
}

.profile-pricing-modal .modal-close {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  padding: 0;
  border: none;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.2);
  color: white;
  font-size: 1.15rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--ls-transition), transform var(--ls-transition);
}

.profile-pricing-modal .modal-close:hover {
  background: rgba(255, 255, 255, 0.35);
  transform: scale(1.05);
}

.profile-pricing-modal .modal-close:focus-visible {
  outline: 2px solid white;
  outline-offset: 2px;
}

.profile-pricing-body {
  padding: 28px 32px 32px !important;
}

.profile-pricing-sub {
  text-align: center;
  color: var(--ls-text-muted);
  margin: 0 0 12px;
  font-size: 0.95rem;
  line-height: 1.5;
}

.profile-pricing-sub--secondary {
  margin: 0 auto 20px;
  max-width: 36rem;
  font-size: 0.88rem;
  color: var(--ls-text-muted);
}

.profile-pricing-otc-foot {
  text-align: center;
  margin: 1.25rem 0 0;
  font-size: 0.9rem;
}

.profile-pricing-otc-foot a {
  color: var(--app-primary);
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.profile-pricing-otc-foot a:hover {
  color: var(--app-primary-dark);
}

.profile-pricing-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
  max-width: 560px;
  margin: 0 auto;
  justify-items: center;
}

.profile-pricing-card {
  background: var(--ls-bg);
  border-radius: var(--ls-radius-lg);
  padding: 32px 28px;
  border: 2px solid var(--ls-border);
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  transition: transform var(--ls-transition), border-color var(--ls-transition);
  width: 100%;
  max-width: 260px;
}

.profile-pricing-card:hover {
  transform: translateY(-2px);
  border-color: var(--app-primary-light);
}

.profile-pricing-featured {
  border-color: var(--app-primary);
  box-shadow: 0 6px 24px rgba(13, 148, 136, 0.12);
}

.profile-pricing-featured:hover {
  border-color: var(--app-primary);
  box-shadow: 0 8px 28px rgba(13, 148, 136, 0.18);
}

.profile-pricing-badge {
  font-size: 0.75rem;
  color: var(--ls-text-muted);
  margin: 0 0 8px;
}

.profile-pricing-badge-featured {
  color: var(--app-primary);
  font-weight: 600;
}

.profile-pricing-savings {
  font-size: 0.9rem;
  font-weight: 700;
  color: #059669;
  margin: 0 0 6px;
  line-height: 1.4;
}

.profile-pricing-name {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--ls-text);
  margin: 0 0 10px;
}

.profile-pricing-price {
  font-size: 2rem;
  font-weight: 800;
  color: var(--ls-text);
  margin: 0 0 8px;
}

.profile-pricing-price span {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--ls-text-muted);
}

.profile-pricing-desc {
  font-size: 0.85rem;
  color: var(--ls-text-muted);
  margin: 0 0 24px;
  flex-grow: 1;
  line-height: 1.5;
}

.profile-pricing-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: fit-content;
  min-width: 120px;
  max-width: calc(100% - 24px);
  padding: 12px 24px;
  margin: 0 auto;
  border: 2px solid var(--app-primary);
  border-radius: var(--ls-radius);
  color: var(--app-primary);
  font-weight: 600;
  font-size: 0.9rem;
  text-decoration: none;
  box-sizing: border-box;
  transition: background var(--ls-transition), color var(--ls-transition), transform var(--ls-transition);
}

.profile-pricing-cta:hover {
  background: var(--app-primary);
  color: white;
  transform: translateY(-1px);
}

.profile-pricing-cta-primary {
  background: linear-gradient(135deg, var(--app-primary) 0%, var(--app-primary-dark) 100%);
  border-color: transparent;
  color: white;
}

.profile-pricing-cta-primary:hover {
  background: linear-gradient(135deg, var(--app-primary-light) 0%, var(--app-primary) 100%);
  color: white;
}

@media (max-width: 640px) {
  .profile-pricing-grid {
    grid-template-columns: 1fr;
    max-width: 100%;
  }
  .profile-pricing-card {
    max-width: 100%;
  }

  .profile-dropdown {
    min-width: 280px;
    max-height: 70vh;
    overflow-y: auto;
  }
}

/* Profile / Change Password modal */
.profile-modal .modal-dialog {
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg);
  font-family: var(--ls-font);
}

.profile-modal .modal-header {
  padding: var(--ls-spacing-lg);
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.profile-modal .modal-title {
  margin: 0;
  font-size: 1.1rem;
}

.profile-modal .modal-body {
  padding: var(--ls-spacing-xl);
}

.profile-modal .form-group {
  margin-bottom: var(--ls-spacing-md);
}

.profile-modal .form-group label {
  display: block;
  margin-bottom: 6px;
  font-weight: 500;
  color: var(--ls-text);
}

.profile-modal .form-group input {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  font-size: 1rem;
  font-family: var(--ls-font);
}

.profile-modal .form-group input:focus {
  outline: none;
  border-color: var(--ls-primary);
  box-shadow: 0 0 0 3px rgba(13, 148, 136, 0.15);
}

.profile-modal .modal-actions {
  display: flex;
  gap: var(--ls-spacing-md);
  margin-top: var(--ls-spacing-lg);
  justify-content: flex-end;
}

.profile-modal .btn-secondary {
  padding: 10px 20px;
  background: var(--ls-bg);
  color: var(--ls-text);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  font-family: var(--ls-font);
  font-weight: 500;
  cursor: pointer;
  transition: background var(--ls-transition);
}

.profile-modal .btn-secondary:hover {
  background: var(--ls-border);
}

.profile-modal .alert-error {
  background: #fef2f2;
  color: #b91c1c;
  padding: 12px;
  border-radius: var(--ls-radius);
  margin-bottom: var(--ls-spacing-md);
}

.profile-modal .alert-success {
  background: #f0fdf4;
  color: #166534;
  padding: 12px;
  border-radius: var(--ls-radius);
  margin-bottom: var(--ls-spacing-md);
}

/* Base modal (Add Student etc) */
.modal {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 1000;
  align-items: center;
  justify-content: center;
  padding: 20px;
  background: rgba(0, 0, 0, 0.5);
}

.modal.show {
  display: flex;
}

.modal-dialog {
  background: white;
  border-radius: 12px;
  max-width: 90%;
  max-height: 90vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.modal-dialog.modal-lg {
  width: 800px;
}

/* Modal - Lesson Selector */
.lesson-modal {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 1000;
  align-items: center;
  justify-content: center;
  padding: var(--ls-spacing-md);
  font-family: var(--ls-font);
}

.lesson-modal.show {
  display: flex;
  animation: modalFadeIn var(--ls-transition) ease-out;
}

.lesson-modal .modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(15, 23, 42, 0.5);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.lesson-modal .modal-dialog {
  position: relative;
  z-index: 1;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  max-width: 90%;
  width: 640px;
  max-height: 90vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  box-shadow: var(--ls-shadow-lg), var(--ls-shadow-glow);
  animation: modalScaleIn var(--ls-transition) ease-out;
}

.lesson-modal.modal-view-lessons .modal-dialog {
  width: 960px;
}

.lesson-modal .modal-content {
  display: flex;
  flex-direction: column;
  max-height: 90vh;
}

.lesson-modal .modal-header {
  padding: var(--ls-spacing-lg) var(--ls-spacing-xl);
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--ls-spacing-md);
}

.lesson-modal .modal-header-content {
  flex: 1;
  min-width: 0;
}

.lesson-modal .modal-title {
  margin: 0 0 var(--ls-spacing-xs);
  font-size: 1.25rem;
  font-weight: 700;
}

.lesson-modal .modal-breadcrumb {
  font-size: 0.8rem;
  font-weight: 500;
  opacity: 0.9;
}

.lesson-modal .modal-breadcrumb a {
  color: inherit;
  text-decoration: none;
}

.lesson-modal .modal-breadcrumb a:hover {
  text-decoration: underline;
}

.lesson-modal .modal-breadcrumb .breadcrumb-sep {
  margin: 0 6px;
  opacity: 0.7;
}

.lesson-modal .modal-close {
  flex-shrink: 0;
  width: var(--ls-touch-min);
  height: var(--ls-touch-min);
  min-width: var(--ls-touch-min);
  min-height: var(--ls-touch-min);
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255,255,255,0.15);
  border: none;
  color: white;
  border-radius: var(--ls-radius);
  cursor: pointer;
  font-size: 1.1rem;
  transition: background var(--ls-transition);
}

.lesson-modal .modal-close:hover {
  background: rgba(255,255,255,0.25);
}

.lesson-modal .modal-body {
  padding: var(--ls-spacing-xl);
  overflow-y: auto;
  flex: 1;
  background: var(--ls-bg);
}

.lesson-modal .modal-footer {
  padding: var(--ls-spacing-md) var(--ls-spacing-xl);
  border-top: 1px solid var(--ls-border);
  background: var(--ls-surface);
}

.lesson-modal .btn-close-modal {
  padding: 12px 24px;
  background: var(--ls-primary);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  font-family: var(--ls-font);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background var(--ls-transition), transform 0.2s;
}

.lesson-modal .btn-close-modal:hover {
  background: var(--ls-primary-dark);
}

/* Modal loading skeleton */
.modal-loading {
  display: flex;
  flex-direction: column;
  gap: var(--ls-spacing-lg);
}

.modal-loading.hidden {
  display: none !important;
}

.skeleton-loader {
  height: 200px;
  background: linear-gradient(90deg, var(--ls-border) 25%, #f1f5f9 50%, var(--ls-border) 75%);
  background-size: 200% 100%;
  animation: skeletonPulse 1.5s ease-in-out infinite;
  border-radius: var(--ls-radius-lg);
}

.skeleton-categories {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--ls-spacing-lg);
}

.skeleton-category {
  height: 140px;
  background: linear-gradient(90deg, var(--ls-border) 25%, #f1f5f9 50%, var(--ls-border) 75%);
  background-size: 200% 100%;
  animation: skeletonPulse 1.5s ease-in-out infinite;
  border-radius: var(--ls-radius-lg);
}

.skeleton-nav {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: var(--ls-spacing-md);
}

.skeleton-nav-item {
  height: 56px;
  background: linear-gradient(90deg, var(--ls-border) 25%, #f1f5f9 50%, var(--ls-border) 75%);
  background-size: 200% 100%;
  animation: skeletonPulse 1.5s ease-in-out infinite;
  border-radius: var(--ls-radius-lg);
}

.skeleton-lesson-card {
  height: 180px;
  background: linear-gradient(90deg, var(--ls-border) 25%, #f1f5f9 50%, var(--ls-border) 75%);
  background-size: 200% 100%;
  animation: skeletonPulse 1.5s ease-in-out infinite;
  border-radius: var(--ls-radius-lg);
}

@keyframes skeletonPulse {
  0%, 100% { background-position: 200% 0; }
  50% { background-position: -200% 0; }
}

@keyframes modalFadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes modalScaleIn {
  from { opacity: 0; transform: scale(0.96); }
  to { opacity: 1; transform: scale(1); }
}

/* View transitions */
.modal-view {
  animation: viewFadeIn 0.35s ease-out;
}

@keyframes viewFadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.hidden {
  display: none !important;
}

/* Category boxes */
.category-list-wrapper {
  display: flex;
  flex-direction: column;
}

.category-list {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--ls-spacing-lg);
}

.category-box {
  min-height: 140px;
  padding: var(--ls-spacing-xl);
  background: var(--cat-gradient, linear-gradient(145deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%));
  text-align: center;
  color: white;
  border-radius: var(--ls-radius-lg);
  cursor: pointer;
  transition: transform var(--ls-transition), box-shadow var(--ls-transition), border-color var(--ls-transition);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--ls-spacing-md);
  box-shadow: 0 8px 24px var(--cat-glow, rgba(13, 148, 136, 0.3));
  border: 1px solid rgba(255,255,255,0.15);
}

.category-box:hover {
  transform: translateY(-6px) scale(1.02);
  box-shadow: 0 16px 40px var(--cat-glow, rgba(13, 148, 136, 0.4));
  border-color: rgba(255,255,255,0.25);
}

.category-box:focus-visible {
  outline: 3px solid rgba(255,255,255,0.6);
  outline-offset: 2px;
}

.category-box img {
  width: 48px;
  height: 48px;
  object-fit: contain;
  filter: brightness(0) invert(1);
  opacity: 0.95;
}

.category-box .category-name {
  font-weight: 600;
  font-size: 1rem;
}

.category-box .category-tagline {
  font-size: 0.75rem;
  opacity: 0.9;
}

.category-list .category-box {
  animation: categoryEnter 0.5s ease-out backwards;
}

@keyframes categoryEnter {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.lesson-grid .lesson-card {
  animation: cardEnter 0.4s ease-out backwards;
}

@keyframes cardEnter {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Chapter nav - grid layout with gradient buttons */
.chapter-nav-wrapper {
  display: flex;
  flex-direction: column;
  gap: var(--ls-spacing-lg);
}

.chapter-nav {
  display: flex;
  flex-direction: column;
  gap: var(--ls-spacing-lg);
}

.chapter-nav .back-btn {
  align-self: flex-start;
  min-height: var(--ls-touch-min);
  padding: 0 var(--ls-spacing-lg);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: linear-gradient(135deg, #64748b 0%, #475569 100%);
  color: white;
  border: none;
  border-radius: var(--ls-radius-lg);
  cursor: pointer;
  font-family: var(--ls-font);
  font-weight: 600;
  font-size: 0.9rem;
  box-shadow: 0 4px 12px rgba(71, 85, 105, 0.3);
  transition: all var(--ls-transition);
}

.chapter-nav .back-btn:hover {
  background: linear-gradient(135deg, #475569 0%, #334155 100%);
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(71, 85, 105, 0.4);
}

.chapter-nav-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: var(--ls-spacing-md);
}

.chapter-nav-grid .nav-item-btn {
  min-height: 56px;
  padding: var(--ls-spacing-md) var(--ls-spacing-lg);
  background: linear-gradient(145deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  border: none;
  border-radius: var(--ls-radius-lg);
  cursor: pointer;
  font-family: var(--ls-font);
  font-weight: 600;
  font-size: 0.95rem;
  text-align: center;
  box-shadow: 0 4px 14px rgba(13, 148, 136, 0.35);
  border: 1px solid rgba(255, 255, 255, 0.15);
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}

.chapter-nav-grid .nav-item-btn:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(13, 148, 136, 0.45);
  background: linear-gradient(145deg, var(--ls-primary-light) 0%, var(--ls-primary) 100%);
}

.chapter-nav-grid .nav-item-btn:focus-visible {
  outline: 2px solid var(--ls-primary);
  outline-offset: 2px;
}

/* Legacy scroll class - now uses grid */
.chapter-nav-scroll {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: var(--ls-spacing-md);
}

.chapter-nav-scroll .nav-item-btn {
  min-height: 56px;
  padding: var(--ls-spacing-md) var(--ls-spacing-lg);
  background: linear-gradient(145deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  border: none;
  border-radius: var(--ls-radius-lg);
  cursor: pointer;
  font-family: var(--ls-font);
  font-weight: 600;
  font-size: 0.95rem;
  text-align: center;
  box-shadow: 0 4px 14px rgba(13, 148, 136, 0.35);
  border: 1px solid rgba(255, 255, 255, 0.15);
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}

.chapter-nav-scroll .nav-item-btn:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(13, 148, 136, 0.45);
  background: linear-gradient(145deg, var(--ls-primary-light) 0%, var(--ls-primary) 100%);
}

/* Lesson grid */
.lesson-grid-wrapper {
  display: flex;
  flex-direction: column;
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: var(--ls-spacing-lg);
}

.lesson-card {
  cursor: pointer;
  border-radius: var(--ls-radius-lg);
  overflow: hidden;
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
  background: var(--ls-surface);
  box-shadow: var(--ls-shadow);
  border: 1px solid var(--ls-border);
  min-height: 200px;
  display: flex;
  flex-direction: column;
}

.lesson-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--ls-shadow-lg), 0 0 0 1px rgba(13, 148, 136, 0.2);
}

.lesson-card:focus-visible {
  outline: 2px solid var(--ls-primary);
  outline-offset: 2px;
}

.lesson-card-thumb-wrap {
  position: relative;
  aspect-ratio: 16 / 10;
  overflow: hidden;
}

.lesson-card-thumb {
  width: 100%;
  height: 100%;
  object-fit: cover;
  background: linear-gradient(135deg, #e0f2f1 0%, #b2dfdb 100%);
}

.lesson-card:hover .lesson-card-overlay {
  opacity: 1;
}

.lesson-card-overlay {
  position: absolute;
  inset: 0;
  background: rgba(13, 148, 136, 0.85);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity var(--ls-transition);
}

.lesson-card-overlay i {
  font-size: 2rem;
  color: white;
}

.lesson-card .lesson-name {
  padding: var(--ls-spacing-md);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--ls-text);
  line-height: 1.4;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.lesson-card-placeholder {
  width: 100%;
  height: 100%;
  min-height: 120px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  font-size: 0.85rem;
  font-weight: 600;
  text-align: center;
  padding: var(--ls-spacing-sm);
}

/* Empty and error states */
.empty-state,
.error-state {
  text-align: center;
  padding: var(--ls-spacing-xl);
}

.empty-state i,
.error-state i {
  font-size: 3rem;
  color: var(--ls-text-muted);
  margin-bottom: var(--ls-spacing-md);
}

.empty-state p,
.error-state p {
  margin: 0 0 var(--ls-spacing-md);
  color: var(--ls-text-muted);
}

.error-message {
  padding: var(--ls-spacing-md);
  background: #fef2f2;
  color: #b91c1c;
  border-radius: var(--ls-radius);
  margin: var(--ls-spacing-md) 0;
}

/* Student Profile modal */
.student-profile-modal {
  display: none;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.student-profile-modal.show {
  display: flex;
}

.student-profile-dialog {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 520px;
  max-height: 90vh;
  overflow-y: auto;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg), 0 0 0 1px var(--ls-border);
  animation: modalScaleIn 0.25s ease-out;
}

.student-profile-modal .modal-header {
  padding: var(--ls-spacing-xl);
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.student-profile-modal .modal-title {
  margin: 0;
  font-size: 1.2rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 10px;
}

.student-profile-modal .modal-close {
  width: 40px;
  height: 40px;
  min-width: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.15);
  border: none;
  color: white;
  border-radius: var(--ls-radius);
  cursor: pointer;
  font-size: 1.1rem;
}

.student-profile-modal .modal-body {
  padding: var(--ls-spacing-xl);
}

.student-profile-modal .form-group {
  margin-bottom: var(--ls-spacing-lg);
}

.student-profile-modal .form-group:last-child {
  margin-bottom: 0;
}

.student-profile-modal .form-group label {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--ls-text);
}

.student-profile-picture-group {
  margin-bottom: 20px;
}
.student-profile-picture-wrap {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}
.student-profile-picture-preview {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: var(--ls-bg);
  border: 2px solid var(--ls-border);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.student-profile-picture-placeholder {
  color: var(--ls-text-muted);
  font-size: 2rem;
}
.student-profile-picture-preview img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.student-profile-picture-actions {
  display: flex;
  gap: 8px;
}
.btn-profile-picture-upload {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  font-size: 0.9rem;
  font-weight: 500;
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: opacity var(--ls-transition);
}
.btn-profile-picture-upload:hover {
  opacity: 0.9;
}
.btn-profile-picture-remove {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  font-size: 0.9rem;
  background: var(--ls-bg);
  color: var(--ls-text-muted);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: background var(--ls-transition), color var(--ls-transition);
}
.btn-profile-picture-remove:hover {
  background: #fee2e2;
  color: #dc2626;
}
.student-profile-modal .form-group label i {
  color: var(--ls-primary);
  font-size: 0.9rem;
}

.student-profile-modal textarea {
  width: 100%;
  padding: 14px 18px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  font-size: 1rem;
  font-family: var(--ls-font);
  resize: vertical;
  min-height: 80px;
}

.student-profile-modal textarea:focus {
  outline: none;
  border-color: var(--ls-primary);
  box-shadow: 0 0 0 3px rgba(13, 148, 136, 0.15);
}

.student-profile-modal .modal-footer {
  padding: var(--ls-spacing-lg) var(--ls-spacing-xl);
  background: var(--ls-bg);
  border-top: 1px solid var(--ls-border);
}

.student-profile-last-lesson-tip {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 20px;
  margin-bottom: var(--ls-spacing-xl);
  background: linear-gradient(135deg, rgba(13, 148, 136, 0.08) 0%, rgba(20, 184, 166, 0.06) 100%);
  border: 1px solid rgba(13, 148, 136, 0.2);
  border-radius: var(--ls-radius-lg);
  border-left: 4px solid var(--ls-primary);
}

.last-lesson-tip-icon {
  width: 44px;
  height: 44px;
  min-width: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--ls-primary);
  color: white;
  border-radius: var(--ls-radius);
  font-size: 1.2rem;
}

.last-lesson-tip-content {
  flex: 1;
  min-width: 0;
}

.last-lesson-tip-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--ls-primary);
  text-transform: uppercase;
  letter-spacing: 0.03em;
  margin-bottom: 4px;
}

.last-lesson-tip-title {
  display: block;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--ls-text);
}

.last-lesson-tip-content .btn-continue-lesson {
  margin-top: 12px;
}

/* Student profile certificates section */
.student-profile-certificates-group {
  margin-top: var(--ls-spacing-lg);
}

.student-profile-certificates {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.student-profile-cert-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--ls-primary);
  background: linear-gradient(135deg, rgba(13, 148, 136, 0.1) 0%, rgba(20, 184, 166, 0.06) 100%);
  border: 1px solid rgba(13, 148, 136, 0.25);
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: background 0.2s, transform 0.15s;
}

.student-profile-cert-item:hover {
  background: linear-gradient(135deg, rgba(13, 148, 136, 0.18) 0%, rgba(20, 184, 166, 0.12) 100%);
  transform: translateY(-1px);
}

.student-profile-cert-item i {
  color: #f59e0b;
}

.student-profile-no-certificates {
  margin: 0;
  padding: 12px;
  font-size: 0.95rem;
  color: var(--ls-text-muted);
}

/* Last lesson notification on main screen */
.last-lesson-notification {
  margin-bottom: 24px;
  animation: slideDown 0.4s ease-out;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.last-lesson-notice {
  display: flex;
  align-items: flex-start;
  gap: 20px;
  padding: 24px 28px;
  background: linear-gradient(135deg, #fefce8 0%, #fef9c3 50%, #fef08a 100%);
  border: 1px solid rgba(245, 158, 11, 0.3);
  border-radius: var(--ls-radius-xl);
  box-shadow: 0 8px 24px rgba(245, 158, 11, 0.15);
  position: relative;
}

.last-lesson-close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  color: var(--ls-text-muted);
  font-size: 1.5rem;
  cursor: pointer;
  border-radius: var(--ls-radius);
  transition: color var(--ls-transition), background var(--ls-transition);
}

.last-lesson-close:hover {
  color: var(--ls-text);
  background: rgba(0, 0, 0, 0.05);
}

.last-lesson-icon {
  width: 56px;
  height: 56px;
  min-width: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: white;
  border-radius: var(--ls-radius-lg);
  font-size: 1.5rem;
}

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

.last-lesson-label {
  margin: 0 0 6px;
  font-size: 0.9rem;
  font-weight: 600;
  color: #92400e;
}

.last-lesson-title {
  margin: 0 0 12px;
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--ls-text);
}

.btn-continue-lesson {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  font-family: var(--ls-font);
  color: white;
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  border: none;
  border-radius: var(--ls-radius);
  cursor: pointer;
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}
.btn-continue-lesson:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(13, 148, 136, 0.4);
}

/* Add Student modal */
.add-student-modal {
  display: none;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.add-student-modal.show {
  display: flex;
}

.add-student-dialog {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 420px;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg), 0 0 0 1px var(--ls-border);
  overflow: hidden;
  animation: modalScaleIn 0.25s ease-out;
}

.add-student-modal .modal-header {
  padding: var(--ls-spacing-xl);
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.add-student-modal .modal-title {
  margin: 0;
  font-size: 1.2rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 10px;
}

.add-student-modal .modal-title i {
  opacity: 0.95;
}

.add-student-modal .modal-close {
  width: 40px;
  height: 40px;
  min-width: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.15);
  border: none;
  color: white;
  border-radius: var(--ls-radius);
  cursor: pointer;
  font-size: 1.1rem;
  transition: background var(--ls-transition);
}

.add-student-modal .modal-close:hover {
  background: rgba(255, 255, 255, 0.25);
}

.add-student-modal .modal-body {
  padding: var(--ls-spacing-xl);
}

.add-student-intro {
  margin: 0 0 var(--ls-spacing-lg);
  font-size: 0.95rem;
  color: var(--ls-text-muted);
  line-height: 1.5;
}

.add-student-modal .form-group {
  margin-bottom: 0;
}

.add-student-modal .form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--ls-text);
}

.add-student-modal .form-group input {
  width: 100%;
  padding: 14px 18px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  font-size: 1rem;
  font-family: var(--ls-font);
}

.add-student-modal .form-group input:focus {
  outline: none;
  border-color: var(--ls-primary);
  box-shadow: 0 0 0 3px rgba(13, 148, 136, 0.15);
}

.add-student-footer {
  display: flex;
  gap: 12px;
  justify-content: flex-end;
  padding: var(--ls-spacing-lg) var(--ls-spacing-xl);
  background: var(--ls-bg);
  border-top: 1px solid var(--ls-border);
}

.add-student-cancel {
  padding: 12px 24px;
  min-height: 44px;
  background: var(--ls-surface);
  color: var(--ls-text);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  font-family: var(--ls-font);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background var(--ls-transition), border-color var(--ls-transition);
}

.add-student-cancel:hover {
  background: var(--ls-bg);
  border-color: var(--ls-text-muted);
}

.add-student-save {
  padding: 12px 24px;
  min-height: 44px;
  background: linear-gradient(135deg, var(--ls-primary) 0%, var(--ls-primary-dark) 100%);
  color: white;
  border: none;
  border-radius: var(--ls-radius);
  font-family: var(--ls-font);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  box-shadow: 0 4px 12px rgba(13, 148, 136, 0.3);
  transition: transform var(--ls-transition), box-shadow var(--ls-transition);
}

.add-student-save:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(13, 148, 136, 0.4);
  color: white;
}

/* Base modal (other modals using modal-sm) */
.modal-dialog.modal-sm {
  width: 400px;
  background: var(--ls-surface);
  border-radius: var(--ls-radius-xl);
  box-shadow: var(--ls-shadow-lg);
  font-family: var(--ls-font);
}

/* Star animation overlay - centered over lesson area */
.star-animation-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
  z-index: 100;
}

.star-animation-overlay.hidden {
  display: none;
}

.star-celebration {
  position: relative;
  animation: starCelebrate 1.4s ease-out forwards;
}

.star-celebration-glow {
  position: absolute;
  inset: -40px;
  background: radial-gradient(circle, rgba(251, 191, 36, 0.4) 0%, transparent 70%);
  animation: starGlow 1.4s ease-out forwards;
}

.star-celebration-core {
  position: relative;
  width: 140px;
  height: 140px;
  display: flex;
  align-items: center;
  justify-content: center;
  filter: drop-shadow(0 0 30px rgba(251, 191, 36, 0.6));
}

.star-celebration-core svg {
  width: 140px;
  height: 140px;
}

.star-sparkles {
  position: absolute;
  inset: -20px;
  pointer-events: none;
}

.star-sparkles .sparkle {
  position: absolute;
  width: 8px;
  height: 8px;
  background: #fbbf24;
  border-radius: 50%;
  animation: sparkleOut 1.2s ease-out forwards;
}

.star-sparkles .s1 { top: 50%; left: 50%; animation-delay: 0.1s; }
.star-sparkles .s2 { top: 20%; left: 50%; animation-delay: 0.15s; }
.star-sparkles .s3 { top: 50%; left: 80%; animation-delay: 0.2s; }
.star-sparkles .s4 { top: 80%; left: 50%; animation-delay: 0.25s; }
.star-sparkles .s5 { top: 50%; left: 20%; animation-delay: 0.2s; }
.star-sparkles .s6 { top: 30%; left: 30%; animation-delay: 0.18s; }
.star-sparkles .s7 { top: 30%; left: 70%; animation-delay: 0.22s; }
.star-sparkles .s8 { top: 70%; left: 70%; animation-delay: 0.2s; }

@keyframes starCelebrate {
  0% { transform: scale(0); opacity: 1; }
  30% { transform: scale(1.15); opacity: 1; }
  60% { transform: scale(1); opacity: 1; }
  100% { transform: scale(1); opacity: 0; }
}

@keyframes starGlow {
  0% { opacity: 0; transform: scale(0.5); }
  30% { opacity: 1; transform: scale(1); }
  100% { opacity: 0; transform: scale(1.2); }
}

@keyframes sparkleOut {
  0% { transform: translate(0, 0) scale(0); opacity: 1; }
  50% { opacity: 1; }
  100% { transform: translate(var(--tx, 0), var(--ty, 0)) scale(1); opacity: 0; }
}

.star-sparkles .s1 { --tx: 0; --ty: -60px; }
.star-sparkles .s2 { --tx: 40px; --ty: -40px; }
.star-sparkles .s3 { --tx: 60px; --ty: 0; }
.star-sparkles .s4 { --tx: 40px; --ty: 40px; }
.star-sparkles .s5 { --tx: -60px; --ty: 0; }
.star-sparkles .s6 { --tx: -40px; --ty: -40px; }
.star-sparkles .s7 { --tx: 40px; --ty: -20px; }
.star-sparkles .s8 { --tx: 30px; --ty: 50px; }

@media (prefers-reduced-motion: reduce) {
  .star-celebration {
    animation: starCelebrateSimple 0.5s ease-out forwards;
  }
  .star-sparkles .sparkle {
    animation: none;
    opacity: 0;
  }
}

@keyframes starCelebrateSimple {
  0% { opacity: 1; }
  100% { opacity: 0; }
}

/* Milestone celebration (50, 100, 150... stars) - Certificate design */
.milestone-celebration-overlay {
  position: fixed;
  inset: 0;
  z-index: 99999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  background: rgba(0, 0, 0, 0.6);
  opacity: 0;
  transition: opacity 0.4s ease;
}
.milestone-celebration-overlay.show {
  opacity: 1;
}
.milestone-confetti-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}
.milestone-celebration-content {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
}
.milestone-certificate-photo {
  margin: 0 auto 20px;
  width: 88px;
  height: 88px;
  border-radius: 50%;
  overflow: hidden;
  border: 4px solid var(--cert-accent, #d97706);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
  flex-shrink: 0;
}
.milestone-certificate-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.milestone-certificate {
  position: relative;
  z-index: 1;
  max-width: 520px;
  width: 100%;
  animation: milestonePop 0.6s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}
@keyframes milestonePop {
  0% {
    transform: scale(0.85);
    opacity: 0;
  }
  100% {
    transform: scale(1);
    opacity: 1;
  }
}
.milestone-certificate-border {
  background: var(--cert-border, linear-gradient(165deg, #fef9c3 0%, #fbbf24 100%));
  padding: 8px;
  border-radius: 4px;
  box-shadow:
    0 0 0 2px rgba(0, 0, 0, 0.2),
    0 0 0 4px rgba(255, 255, 255, 0.3),
    0 25px 60px rgba(0, 0, 0, 0.35),
    inset 0 1px 0 rgba(255, 255, 255, 0.6);
}
.milestone-certificate-inner {
  background: var(--cert-inner, linear-gradient(180deg, #fffbeb 0%, #fef3c7 100%));
  padding: 48px 44px 40px;
  border-radius: 2px;
  text-align: center;
  box-shadow: inset 0 0 80px rgba(0, 0, 0, 0.05);
}
.milestone-certificate-header {
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 2px double var(--cert-accent, #d97706);
}
.milestone-certificate-icon {
  display: flex;
  justify-content: center;
  margin-bottom: 16px;
  font-size: 3.5rem;
  color: var(--cert-accent, #b45309);
  animation: milestoneStars 0.6s ease 0.2s both;
}
@keyframes milestoneStars {
  0% {
    transform: scale(0) rotate(-180deg);
    opacity: 0;
  }
  100% {
    transform: scale(1) rotate(0deg);
    opacity: 1;
  }
}
.milestone-certificate-title {
  margin: 0 0 12px;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--cert-accent, #92400e);
  text-transform: uppercase;
}
.milestone-certificate-badge {
  display: inline-block;
  padding: 6px 20px;
  font-size: 1.1rem;
  font-weight: 800;
  color: var(--cert-accent, #78350f);
  background: var(--cert-badge, #fcd34d);
  border: 2px solid var(--cert-accent, #d97706);
  border-radius: 4px;
  letter-spacing: 0.05em;
}
.milestone-certificate-line1 {
  margin: 0 0 8px;
  font-size: 1.35rem;
  font-weight: 700;
  line-height: 1.4;
  color: #292524;
}
.milestone-certificate-line2 {
  margin: 0 0 28px;
  font-size: 1.2rem;
  font-weight: 600;
  line-height: 1.5;
  color: #292524;
}
.milestone-certificate-teacher {
  margin: 0 0 28px;
  font-size: 1rem;
  font-style: italic;
  color: #78716c;
}
.milestone-certificate-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-top: 24px;
  padding-top: 8px;
}
.btn-milestone-download {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--ls-font);
  color: #78350f;
  background: rgba(255, 255, 255, 0.9);
  border: 2px solid #d97706;
  border-radius: 8px;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
}
.btn-milestone-download:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(180, 83, 9, 0.3);
}
.btn-milestone-download:disabled {
  opacity: 0.7;
  cursor: not-allowed;
  transform: none;
}
.btn-milestone-close {
  padding: 14px 36px;
  font-size: 1.1rem;
  font-weight: 700;
  font-family: var(--ls-font);
  color: #78350f;
  background: linear-gradient(135deg, #fcd34d 0%, #f59e0b 100%);
  border: 2px solid #d97706;
  border-radius: var(--ls-radius);
  cursor: pointer;
  box-shadow: 0 4px 16px rgba(180, 83, 9, 0.35);
  transition: transform 0.2s, box-shadow 0.2s;
}
.btn-milestone-close:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(180, 83, 9, 0.45);
}

/* Responsive - Lesson selector */
@media (max-width: 1024px) {
  .lesson-modal .modal-dialog {
    width: 90%;
    max-width: 720px;
  }
  .lesson-modal.modal-view-lessons .modal-dialog {
    width: 95%;
    max-width: none;
  }
  .category-list {
    grid-template-columns: repeat(2, 1fr);
  }
  .lesson-grid {
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  }
}

@media (max-width: 768px) {
  .lesson-modal {
    padding: 0;
    align-items: flex-end;
  }
  .lesson-modal .modal-dialog {
    width: 100%;
    max-width: 100%;
    max-height: 92vh;
    border-radius: var(--ls-radius-xl) var(--ls-radius-xl) 0 0;
  }
  .lesson-modal .modal-header {
    padding: var(--ls-spacing-md) var(--ls-spacing-lg);
  }
  .lesson-modal .modal-body {
    padding: var(--ls-spacing-lg);
  }
  .category-list {
    grid-template-columns: 1fr;
    gap: var(--ls-spacing-md);
  }
  .category-box {
    min-height: 120px;
  }
  .chapter-nav-scroll,
  .chapter-nav-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--ls-spacing-sm);
  }
  .lesson-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--ls-spacing-md);
  }
}

@media (max-width: 480px) {
  .lesson-grid {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  .lesson-modal.show,
  .lesson-modal .modal-dialog,
  .category-box,
  .lesson-card,
  .chapter-nav .back-btn,
  .chapter-nav .nav-item-btn {
    animation: none;
  }
  .lesson-modal .modal-dialog {
    animation: none;
  }
}

/* Responsive - Navbar and general */
@media (max-width: 768px) {
  .navbar-inner {
    flex-direction: column;
    flex-wrap: wrap;
    align-items: stretch;
    gap: 8px;
  }
  .nav-left {
    flex-shrink: 0;
  }
  .nav-right {
    width: 100%;
    flex-wrap: wrap;
  }
  .student-selector-trigger {
    min-width: 0;
    flex: 1;
  }
  .student-dropdown {
    min-width: 100%;
  }
  .star-award-bar {
    width: 100%;
    flex-wrap: wrap;
    justify-content: flex-start;
    padding: 6px 12px;
    gap: 8px;
  }
  .star-slot {
    width: 28px;
    height: 28px;
    font-size: 1rem;
  }
  .star-session-badge {
    font-size: 0.8rem;
    min-width: 0;
    padding: 4px 8px;
  }
  .add-student-dialog {
    max-width: 100%;
  }
  .choose-lesson-section {
    padding-top: 24px;
  }
  .lesson-viewer,
  .lesson-placeholder,
  .lesson-embed {
    min-height: 360px;
  }
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-10px); }
  to { opacity: 1; transform: translateY(0); }
}