:root {
  --bg: #f8fafc;
  --bg-elevated: #ffffff;
  --bg-subtle: #f1f5f9;
  --text: #0f172a;
  --text-muted: #475569;
  --border: #e2e8f0;
  --primary: #dc2626;
  --primary-dark: #b91c1c;
  --primary-soft: #fef2f2;
  --accent: #f59e0b;
  --accent-soft: #fffbeb;
  --success: #16a34a;
  --success-soft: #f0fdf4;
  --danger: #dc2626;
  --danger-soft: #fef2f2;
  --shadow-sm: 0 2px 8px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.09);
  --radius-md: 14px;
  --radius-lg: 20px;
}

[data-theme="dark"] {
  --bg: #0b1120;
  --bg-elevated: #1e293b;
  --bg-subtle: #0f172a;
  --text: #f8fafc;
  --text-muted: #94a3b8;
  --border: #334155;
  --primary: #ef4444;
  --primary-dark: #dc2626;
  --primary-soft: rgba(239, 68, 68, 0.15);
  --accent: #fbbf24;
  --accent-soft: rgba(251, 191, 36, 0.14);
  --success: #22c55e;
  --success-soft: rgba(34, 197, 94, 0.16);
  --danger: #f87171;
  --danger-soft: rgba(248, 113, 113, 0.16);
  --shadow-sm: 0 2px 10px rgba(0, 0, 0, 0.35);
  --shadow-md: 0 10px 28px rgba(0, 0, 0, 0.45);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

html, body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.45;
  min-height: 100vh;
  padding-bottom: calc(74px + env(safe-area-inset-bottom, 0px));
}

/* Header */
.app-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: linear-gradient(135deg, #b91c1c 0%, #dc2626 60%, #ea580c 100%);
  color: #ffffff;
  padding: calc(10px + env(safe-area-inset-top, 0px)) 16px 12px;
  box-shadow: 0 4px 16px rgba(185, 28, 28, 0.28);
}

.header-inner {
  max-width: 680px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 11px;
  cursor: pointer;
}

.brand-logo {
  width: 42px;
  height: 42px;
  border-radius: 11px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.25);
  flex-shrink: 0;
}

.brand-badge {
  display: inline-block;
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  background: rgba(255, 255, 255, 0.2);
  padding: 2px 7px;
  border-radius: 99px;
  margin-bottom: 2px;
}

.brand-text h1 {
  font-size: 1.15rem;
  font-weight: 800;
  line-height: 1.15;
}

.sub-highlight {
  color: #fde047;
}

.header-actions {
  display: flex;
  gap: 8px;
}

.icon-btn {
  width: 40px;
  height: 40px;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.25);
  background: rgba(255, 255, 255, 0.14);
  color: #fff;
  font-size: 1.15rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform 0.15s ease, background 0.15s ease;
}

.icon-btn:active {
  transform: scale(0.92);
}

/* Main Content */
.app-main {
  max-width: 680px;
  margin: 0 auto;
  padding: 16px 14px 28px;
}

.view {
  display: none;
  animation: fadeIn 0.2s ease;
}

.view.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

.hidden {
  display: none !important;
}

/* Install Banner */
.install-banner {
  background: linear-gradient(135deg, #1e293b, #0f172a);
  color: #fff;
  border-radius: var(--radius-md);
  padding: 12px 14px;
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  border: 1px solid #334155;
  box-shadow: var(--shadow-sm);
}

.install-banner-content {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.85rem;
}

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

.install-banner-content p {
  color: #cbd5e1;
  font-size: 0.78rem;
  margin-top: 2px;
}

.btn-install {
  background: #fde047;
  color: #0f172a;
  border: none;
  font-weight: 800;
  padding: 9px 14px;
  border-radius: 10px;
  cursor: pointer;
  white-space: nowrap;
}

/* Hero Card */
.hero-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 16px;
  box-shadow: var(--shadow-sm);
  margin-bottom: 18px;
}

.hero-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 14px;
}

.rank-badge-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
}

.rank-emoji {
  width: 50px;
  height: 50px;
  border-radius: 14px;
  background: var(--primary-soft);
  border: 2px solid var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.65rem;
}

.rank-label {
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  color: var(--primary);
}

.rank-title {
  font-size: 1.05rem;
  font-weight: 800;
}

.streak-pill {
  background: var(--accent-soft);
  color: #d97706;
  border: 1px solid rgba(245, 158, 11, 0.35);
  padding: 6px 11px;
  border-radius: 99px;
  font-weight: 800;
  font-size: 0.85rem;
  white-space: nowrap;
}

[data-theme="dark"] .streak-pill {
  color: #fde047;
}

.mastery-progress-wrap {
  margin-bottom: 14px;
}

.mastery-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.84rem;
  margin-bottom: 6px;
  color: var(--text-muted);
}

.mastery-labels strong {
  color: var(--text);
}

.progress-bar-bg {
  width: 100%;
  height: 12px;
  background: var(--bg-subtle);
  border-radius: 99px;
  overflow: hidden;
  border: 1px solid var(--border);
}

.progress-bar-bg.slim {
  height: 8px;
  margin-bottom: 14px;
}

.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, #dc2626, #f59e0b);
  border-radius: 99px;
  transition: width 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

.stats-grid-mini {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.stat-box {
  background: var(--bg-subtle);
  border-radius: 12px;
  padding: 9px 6px;
  text-align: center;
}

.stat-num {
  display: block;
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--text);
}

.stat-lbl {
  font-size: 0.72rem;
  color: var(--text-muted);
}

/* Section Heading */
.section-heading {
  font-size: 1rem;
  font-weight: 800;
  margin: 18px 2px 10px;
  color: var(--text);
}

/* Modes Grid */
.modes-grid {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 18px;
}

.mode-card {
  width: 100%;
  background: var(--bg-elevated);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-md);
  padding: 14px;
  display: flex;
  align-items: center;
  gap: 13px;
  text-align: left;
  cursor: pointer;
  color: var(--text);
  box-shadow: var(--shadow-sm);
  transition: transform 0.12s ease, border-color 0.15s ease;
}

.mode-card:active {
  transform: scale(0.985);
}

.mode-card.mode-primary {
  border-left: 5px solid #dc2626;
}

.mode-card.mode-competition {
  border-left: 5px solid #f59e0b;
}

.mode-card.mode-smart {
  border-left: 5px solid #2563eb;
}

.mode-card.mode-flashcards {
  border-left: 5px solid #16a34a;
}

.mode-icon {
  font-size: 1.85rem;
  width: 46px;
  height: 46px;
  border-radius: 12px;
  background: var(--bg-subtle);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.mode-info {
  flex: 1;
}

.mode-title-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.mode-info h3 {
  font-size: 0.98rem;
  font-weight: 800;
  margin-bottom: 3px;
}

.mode-info p {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.badge-pill {
  background: var(--primary);
  color: #fff;
  font-size: 0.72rem;
  font-weight: 800;
  padding: 2px 8px;
  border-radius: 99px;
}

.mode-arrow {
  font-weight: 800;
  color: var(--text-muted);
  font-size: 1.1rem;
}

/* Tricky Questions Callout */
.tricky-callout {
  background: var(--accent-soft);
  border: 1.5px solid rgba(245, 158, 11, 0.45);
  border-radius: var(--radius-md);
  padding: 13px 14px;
  margin-bottom: 18px;
}

.tricky-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 8px;
  font-size: 0.88rem;
}

.btn-small-outline {
  background: var(--bg-elevated);
  color: var(--text);
  border: 1px solid var(--accent);
  border-radius: 8px;
  padding: 5px 10px;
  font-size: 0.76rem;
  font-weight: 700;
  cursor: pointer;
  white-space: nowrap;
}

.tricky-list {
  padding-left: 18px;
  font-size: 0.8rem;
  color: var(--text);
  display: flex;
  flex-direction: column;
  gap: 5px;
}

/* Categories List */
.categories-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 8px;
  margin-bottom: 18px;
}

.cat-item-btn {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 11px 14px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  cursor: pointer;
  color: var(--text);
  text-align: left;
}

.cat-item-left {
  display: flex;
  align-items: center;
  gap: 10px;
}

.cat-name {
  font-weight: 700;
  font-size: 0.9rem;
}

.cat-count {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-weight: 600;
}

/* Verified Card */
.verified-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 14px;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.verified-badge {
  display: inline-block;
  background: var(--success-soft);
  color: var(--success);
  font-weight: 800;
  font-size: 0.72rem;
  padding: 4px 9px;
  border-radius: 99px;
  margin-bottom: 8px;
}

.verified-actions {
  margin-top: 12px;
  padding-top: 10px;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}

.btn-text-danger, .btn-text-link {
  background: none;
  border: none;
  font-size: 0.78rem;
  font-weight: 700;
  cursor: pointer;
}

.btn-text-danger { color: var(--danger); }
.btn-text-link { color: var(--primary); }

/* Quiz Toolbar */
.quiz-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}

.btn-chip {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 12px;
  border-radius: 99px;
  font-size: 0.82rem;
  font-weight: 700;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  box-shadow: var(--shadow-sm);
}

/* Question Card */
.question-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 18px 16px;
  box-shadow: var(--shadow-md);
}

.q-meta-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}

.q-number-badge {
  background: var(--primary-soft);
  color: var(--primary);
  font-weight: 800;
  font-size: 0.8rem;
  padding: 4px 10px;
  border-radius: 99px;
}

.q-cat-badge {
  background: var(--bg-subtle);
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 99px;
}

.q-title {
  font-size: 1.15rem;
  font-weight: 800;
  margin-bottom: 16px;
  line-height: 1.38;
}

/* Answer Options */
.options-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 16px;
}

.option-btn {
  width: 100%;
  min-height: 56px;
  background: var(--bg-subtle);
  border: 2px solid var(--border);
  border-radius: 14px;
  padding: 12px 14px;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  text-align: left;
  color: var(--text);
  font-size: 0.96rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
}

.option-btn:hover:not(:disabled) {
  border-color: var(--primary);
}

.option-btn:active:not(:disabled) {
  transform: scale(0.99);
}

.opt-letter {
  width: 30px;
  height: 30px;
  border-radius: 9px;
  background: var(--bg-elevated);
  border: 1.5px solid var(--border);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 0.88rem;
  flex-shrink: 0;
  text-transform: uppercase;
}

.opt-text {
  flex: 1;
  padding-top: 3px;
}

.option-btn.selected {
  border-color: #2563eb;
  background: rgba(37, 99, 235, 0.1);
}

.option-btn.selected .opt-letter {
  background: #2563eb;
  color: #fff;
  border-color: #2563eb;
}

.option-btn.correct {
  border-color: var(--success);
  background: var(--success-soft);
}

.option-btn.correct .opt-letter {
  background: var(--success);
  color: #fff;
  border-color: var(--success);
}

.option-btn.wrong {
  border-color: var(--danger);
  background: var(--danger-soft);
}

.option-btn.wrong .opt-letter {
  background: var(--danger);
  color: #fff;
  border-color: var(--danger);
}

/* Feedback Box */
.feedback-box {
  border-radius: 14px;
  padding: 14px;
  margin-bottom: 16px;
  border: 1.5px solid var(--border);
  background: var(--bg-subtle);
  animation: fadeIn 0.2s ease;
}

.feedback-box.is-correct {
  border-color: var(--success);
  background: var(--success-soft);
}

.feedback-box.is-wrong {
  border-color: var(--danger);
  background: var(--danger-soft);
}

.feedback-header {
  font-weight: 800;
  font-size: 0.95rem;
  margin-bottom: 6px;
}

.feedback-explanation {
  font-size: 0.88rem;
  margin-bottom: 8px;
  color: var(--text);
}

.feedback-source {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-muted);
}

/* Navigation Footer inside Card */
.q-nav-footer {
  display: grid;
  grid-template-columns: 1fr 1.3fr;
  gap: 10px;
}

.btn-primary, .btn-secondary {
  min-height: 48px;
  border-radius: 12px;
  font-size: 0.95rem;
  font-weight: 800;
  cursor: pointer;
  border: none;
  padding: 10px 16px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.btn-primary {
  background: linear-gradient(135deg, #dc2626, #ea580c);
  color: #fff;
  box-shadow: 0 4px 12px rgba(220, 38, 38, 0.28);
}

.btn-secondary {
  background: var(--bg-subtle);
  color: var(--text);
  border: 1.5px solid var(--border);
}

.btn-large {
  width: 100%;
  min-height: 54px;
  font-size: 1.02rem;
  margin-top: 10px;
}

/* Exam Mode Panels */
.card-panel {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 22px 18px;
  text-align: center;
  box-shadow: var(--shadow-md);
}

.panel-header-icon, .result-medal {
  font-size: 3.2rem;
  margin-bottom: 8px;
}

.panel-subtitle {
  color: var(--text-muted);
  font-size: 0.86rem;
  margin-bottom: 18px;
}

.setup-options {
  text-align: left;
  margin-bottom: 16px;
}

.setup-label {
  display: block;
  font-weight: 800;
  font-size: 0.88rem;
  margin-bottom: 8px;
}

.segmented-control {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.seg-btn {
  background: var(--bg-subtle);
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: 10px 6px;
  font-weight: 800;
  font-size: 0.88rem;
  color: var(--text);
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}

.seg-btn small {
  font-weight: 500;
  font-size: 0.7rem;
  color: var(--text-muted);
}

.seg-btn.active {
  border-color: var(--primary);
  background: var(--primary-soft);
  color: var(--primary);
}

.toggle-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 11px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
}

.toggle-row input[type="checkbox"] {
  width: 22px;
  height: 22px;
  accent-color: var(--primary);
}

.exam-top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
  font-size: 0.9rem;
}

.exam-timer {
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  background: var(--bg-elevated);
  padding: 4px 10px;
  border-radius: 99px;
  border: 1px solid var(--border);
}

.btn-quit-exam {
  background: none;
  border: none;
  color: var(--danger);
  font-weight: 700;
  cursor: pointer;
}

.result-score-big {
  font-size: 2rem;
  font-weight: 900;
  color: var(--primary);
  margin: 8px 0 4px;
}

.result-meta {
  color: var(--text-muted);
  font-size: 0.88rem;
  margin-bottom: 16px;
}

.result-actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 22px;
}

.review-heading {
  text-align: left;
  font-size: 1rem;
  margin-bottom: 10px;
}

.review-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  text-align: left;
}

.review-item {
  background: var(--bg-subtle);
  border-radius: 12px;
  padding: 12px;
  border-left: 4px solid var(--border);
  font-size: 0.86rem;
}

.review-item.rev-ok { border-left-color: var(--success); }
.review-item.rev-bad { border-left-color: var(--danger); }

.review-q {
  font-weight: 800;
  margin-bottom: 6px;
}

/* Flashcards 3D */
.flashcard-stage {
  perspective: 1200px;
  margin-bottom: 16px;
}

.flashcard {
  width: 100%;
  min-height: 360px;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.5s cubic-bezier(0.22, 1, 0.36, 1);
  cursor: pointer;
}

.flashcard.is-flipped {
  transform: rotateY(180deg);
}

.fc-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  background: var(--bg-elevated);
  border: 2px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 20px 18px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-md);
}

.fc-back {
  transform: rotateY(180deg);
  border-color: var(--success);
}

.fc-top-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.fc-question-body h2 {
  font-size: 1.15rem;
  margin-bottom: 14px;
}

.fc-options-preview {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 0.86rem;
  color: var(--text-muted);
}

.fc-correct-pill {
  background: var(--success-soft);
  color: var(--success);
  font-weight: 800;
  font-size: 0.76rem;
  padding: 4px 10px;
  border-radius: 99px;
}

.fc-answer-highlight {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--success);
  margin-bottom: 12px;
  padding: 12px;
  background: var(--success-soft);
  border-radius: 12px;
}

.fc-explanation {
  font-size: 0.9rem;
  margin-bottom: 10px;
}

.fc-source {
  font-size: 0.76rem;
  color: var(--text-muted);
  font-weight: 700;
}

.fc-tap-hint {
  text-align: center;
  font-size: 0.78rem;
  color: var(--text-muted);
  font-weight: 600;
}

.fc-controls {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.btn-fc {
  min-height: 52px;
  border-radius: 14px;
  font-weight: 800;
  font-size: 0.92rem;
  cursor: pointer;
  border: none;
}

.btn-fc-hard {
  background: var(--accent-soft);
  color: #d97706;
  border: 1.5px solid var(--accent);
}

.btn-fc-easy {
  background: var(--success);
  color: #fff;
}

/* Catalog View (All 80 Questions) */
.catalog-controls {
  position: sticky;
  top: 66px;
  z-index: 20;
  background: var(--bg);
  padding: 6px 0 12px;
}

.search-input-wrap {
  position: relative;
  margin-bottom: 8px;
}

.search-icon {
  position: absolute;
  left: 13px;
  top: 50%;
  transform: translateY(-50%);
}

#catalog-search {
  width: 100%;
  height: 46px;
  border-radius: 12px;
  border: 1.5px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text);
  padding: 0 14px 0 40px;
  font-size: 0.92rem;
}

.catalog-filter-row {
  display: flex;
  gap: 8px;
}

.select-pill {
  flex: 1;
  height: 40px;
  border-radius: 99px;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text);
  padding: 0 12px;
  font-weight: 700;
  font-size: 0.82rem;
}

.catalog-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.catalog-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 14px;
  box-shadow: var(--shadow-sm);
}

.catalog-q-title {
  font-weight: 800;
  font-size: 0.98rem;
  margin: 8px 0 10px;
}

.catalog-opts {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 5px;
  font-size: 0.86rem;
}

.catalog-opt {
  padding: 7px 10px;
  border-radius: 9px;
  background: var(--bg-subtle);
}

.catalog-opt.is-correct-opt {
  background: var(--success-soft);
  color: var(--success);
  font-weight: 800;
  border: 1px solid var(--success);
}

.catalog-list.hide-answers .catalog-opt.is-correct-opt {
  background: var(--bg-subtle);
  color: var(--text);
  font-weight: 400;
  border: none;
}

.catalog-list.hide-answers .catalog-exp {
  display: none;
}

.catalog-card.revealed .catalog-opt.is-correct-opt {
  background: var(--success-soft) !important;
  color: var(--success) !important;
  font-weight: 800 !important;
  border: 1px solid var(--success) !important;
}

.catalog-card.revealed .catalog-exp {
  display: block !important;
}

.catalog-exp {
  margin-top: 10px;
  padding-top: 8px;
  border-top: 1px dashed var(--border);
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Modals */
.modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 100;
  background: rgba(15, 23, 42, 0.65);
  backdrop-filter: blur(3px);
  display: flex;
  align-items: flex-end;
  justify-content: center;
}

.modal-sheet {
  width: 100%;
  max-width: 680px;
  max-height: 82vh;
  background: var(--bg-elevated);
  border-radius: 22px 22px 0 0;
  padding: 18px 16px calc(22px + env(safe-area-inset-bottom, 0px));
  overflow-y: auto;
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
}

.modal-header .icon-btn {
  background: var(--bg-subtle);
  color: var(--text);
}

.grid-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.76rem;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.dot {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  margin-right: 4px;
}

.dot-mastered { background: var(--success); }
.dot-learning { background: #3b82f6; }
.dot-wrong { background: var(--danger); }
.dot-unseen { background: #94a3b8; }

.q-number-grid {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  gap: 7px;
}

.grid-num-btn {
  height: 40px;
  border-radius: 10px;
  border: 1.5px solid var(--border);
  background: var(--bg-subtle);
  color: var(--text);
  font-weight: 800;
  font-size: 0.85rem;
  cursor: pointer;
}

.grid-num-btn.st-mastered { background: var(--success-soft); border-color: var(--success); color: var(--success); }
.grid-num-btn.st-learning { background: rgba(59, 130, 246, 0.14); border-color: #3b82f6; color: #3b82f6; }
.grid-num-btn.st-wrong { background: var(--danger-soft); border-color: var(--danger); color: var(--danger); }

.filter-options-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.filter-opt-btn {
  width: 100%;
  padding: 13px 14px;
  border-radius: 12px;
  border: 1.5px solid var(--border);
  background: var(--bg-subtle);
  color: var(--text);
  font-weight: 700;
  text-align: left;
  display: flex;
  justify-content: space-between;
  cursor: pointer;
}

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

.install-steps {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.install-os-block {
  background: var(--bg-subtle);
  padding: 14px;
  border-radius: 14px;
}

.install-os-block h4 {
  margin-bottom: 8px;
}

.install-os-block ol {
  padding-left: 18px;
  font-size: 0.88rem;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

/* Bottom Navigation Bar */
.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 50;
  background: var(--bg-elevated);
  border-top: 1px solid var(--border);
  padding: 6px 8px calc(6px + env(safe-area-inset-bottom, 0px));
  display: flex;
  justify-content: space-around;
  box-shadow: 0 -4px 16px rgba(15, 23, 42, 0.06);
}

.nav-item {
  flex: 1;
  max-width: 120px;
  background: none;
  border: none;
  color: var(--text-muted);
  padding: 6px 4px;
  border-radius: 12px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3px;
  cursor: pointer;
  font-weight: 700;
  transition: color 0.15s ease, background 0.15s ease;
}

.nav-item.active {
  color: var(--primary);
  background: var(--primary-soft);
}

.nav-icon {
  font-size: 1.25rem;
  line-height: 1;
}

.nav-label {
  font-size: 0.7rem;
}

@media (max-width: 380px) {
  .q-number-grid {
    grid-template-columns: repeat(6, 1fr);
  }
}