:root {
  --primary: #059669;
  --primary-hover: #047857;
  --primary-light: #d1fae5;
  --primary-focus: rgba(5, 150, 105, 0.2);
  --secondary: #4f46e5;
  --secondary-light: #e0e7ff;
  --accent: #0ea5e9;
  --warning: #f59e0b;
  --warning-light: #fef3c7;
  --danger: #ef4444;
  --danger-light: #fee2e2;
  --bg: #f8fafc;
  --surface: #ffffff;
  --surface-alt: #f1f5f9;
  --border: #e2e8f0;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --text-light: #94a3b8;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-heading: 'Outfit', 'Inter', sans-serif;
}

[data-theme="dark"] {
  --bg: #090d16;
  --surface: #111827;
  --surface-alt: #1f2937;
  --border: #374151;
  --text-main: #f9fafb;
  --text-muted: #9ca3af;
  --text-light: #6b7280;
  --primary-light: rgba(5, 150, 105, 0.2);
  --secondary-light: rgba(79, 70, 229, 0.2);
  --warning-light: rgba(245, 158, 11, 0.2);
  --danger-light: rgba(239, 68, 68, 0.2);
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.5);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.6);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.8);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg);
  color: var(--text-main);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background-color 0.25s ease, color 0.25s ease;
}

/* NAVBAR HEADER */
header.app-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 50;
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(8px);
}

.header-container {
  max-width: 1440px;
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.header-top-row {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.brand-section {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.brand-logo {
  width: 42px;
  height: 42px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.35rem;
  box-shadow: 0 4px 10px rgba(5, 150, 105, 0.3);
  flex-shrink: 0;
}

.brand-titles h1 {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-main);
  letter-spacing: -0.02em;
  white-space: nowrap;
}

.brand-titles .subtitle {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
  white-space: nowrap;
}

.nav-tabs {
  display: flex;
  background: var(--surface-alt);
  padding: 0.25rem;
  border-radius: var(--radius-full);
  gap: 0.25rem;
  overflow-x: auto;
  white-space: nowrap;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  -ms-overflow-style: none;
}

.nav-tabs::-webkit-scrollbar {
  display: none;
}

.tab-btn {
  background: transparent;
  border: none;
  padding: 0.45rem 1rem;
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  transition: all 0.2s ease;
  white-space: nowrap;
  flex-shrink: 0;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.tab-btn:hover {
  color: var(--text-main);
}

.tab-btn.active {
  background: var(--surface);
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.btn-icon {
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text-main);
  width: 38px;
  height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 1.1rem;
  transition: all 0.2s ease;
}

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

/* TIMER WIDGET */
.timer-badge {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--primary-light);
  color: var(--primary);
  border: 1px solid currentColor;
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-full);
  font-family: monospace;
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  transition: all 0.3s ease;
}

.timer-badge.warning {
  background: var(--danger-light);
  color: var(--danger);
  animation: pulse-danger 1.5s infinite;
}

.timer-badge.paused {
  border-style: dashed;
  background: rgba(245, 158, 11, 0.15);
  color: #b45309;
}

[data-theme="dark"] .timer-badge.paused {
  color: #fbbf24;
}

@keyframes pulse-danger {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.85; transform: scale(1.03); }
}

/* TIMER ACTION BUTTON IN HEADER */
.btn-timer-action {
  height: 38px;
  padding: 0 1rem;
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.2s ease;
  white-space: nowrap;
}

/* State: Start (Green gradient, enticing) */
.btn-timer-action.state-start {
  background: linear-gradient(135deg, #059669 0%, #047857 100%);
  color: white;
  box-shadow: 0 2px 8px rgba(5, 150, 105, 0.35);
}
.btn-timer-action.state-start:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(5, 150, 105, 0.45);
}

/* State: Running (Shows Pause option) */
.btn-timer-action.state-running {
  background: rgba(245, 158, 11, 0.15);
  color: #b45309;
  border-color: #f59e0b;
}
[data-theme="dark"] .btn-timer-action.state-running {
  background: rgba(245, 158, 11, 0.2);
  color: #fbbf24;
}
.btn-timer-action.state-running:hover {
  background: rgba(245, 158, 11, 0.25);
  transform: translateY(-1px);
}

/* State: Paused (Shows Resume option with pulse) */
.btn-timer-action.state-paused {
  background: linear-gradient(135deg, #10b981 0%, #059669 100%);
  color: white;
  animation: pulse-resume 1.5s infinite;
  box-shadow: 0 2px 8px rgba(16, 185, 129, 0.35);
}

@keyframes pulse-resume {
  0%, 100% { transform: scale(1); box-shadow: 0 0 0 0 rgba(16, 185, 129, 0.4); }
  50% { transform: scale(1.02); box-shadow: 0 0 0 6px rgba(16, 185, 129, 0); }
}

/* EXAM NOT STARTED & PAUSE SHIELD */
.exam-not-started-banner {
  background: var(--primary-light);
  border: 1px solid var(--primary);
  border-radius: var(--radius-md);
  padding: 0.75rem 1rem;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  font-size: 0.88rem;
  color: var(--primary-dark);
  animation: fadeIn 0.3s ease;
}
[data-theme="dark"] .exam-not-started-banner {
  color: #6ee7b7;
}

.exam-pause-shield {
  background: var(--surface);
  border: 2px dashed #f59e0b;
  border-radius: var(--radius-lg);
  padding: 2.75rem 1.5rem;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  margin: 1.25rem 0;
  box-shadow: var(--shadow-sm);
  animation: fadeIn 0.3s ease;
}

.pause-icon-big {
  font-size: 2.8rem;
  width: 68px;
  height: 68px;
  border-radius: 50%;
  background: rgba(245, 158, 11, 0.15);
  display: flex;
  align-items: center;
  justify-content: center;
}

.pause-title {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-main);
}

.pause-desc {
  font-size: 0.92rem;
  color: var(--text-muted);
  max-width: 480px;
  line-height: 1.5;
}

.pause-time-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  padding: 0.45rem 1.25rem;
  font-size: 0.95rem;
  color: var(--text-main);
  font-family: monospace;
  font-weight: 700;
}

/* TTS AUDIO READING BUTTON */
.btn-speak-exp {
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 600;
  background: var(--surface);
  border: 1.5px solid var(--secondary);
  color: var(--secondary);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  transition: all 0.2s ease;
  flex-shrink: 0;
  user-select: none;
}

.btn-speak-exp:hover {
  background: var(--secondary-light);
  transform: translateY(-1px);
}

.btn-speak-exp.is-speaking {
  background: #ef4444 !important;
  border-color: #ef4444 !important;
  color: white !important;
  animation: pulse-speaking 1.2s infinite;
  box-shadow: 0 2px 10px rgba(239, 68, 68, 0.4);
}

@keyframes pulse-speaking {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.88; transform: scale(1.03); }
}

/* MAIN LAYOUT */
main.app-main {
  flex: 1;
  max-width: 1440px;
  margin: 0 auto;
  width: 100%;
  padding: 1.25rem 1.5rem;
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 1.5rem;
}

/* LEFT COLUMN: EXAM VIEW */
.exam-container {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  min-width: 0;
  max-width: 100%;
}

.exam-controls-bar {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 0.85rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
  flex-wrap: wrap;
  gap: 0.75rem;
}

.progress-info {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex: 1;
  min-width: 250px;
}

.progress-text {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  white-space: nowrap;
}

.progress-track {
  flex: 1;
  height: 8px;
  background: var(--surface-alt);
  border-radius: var(--radius-full);
  overflow: hidden;
  border: 1px solid var(--border);
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--primary) 0%, var(--accent) 100%);
  border-radius: var(--radius-full);
  transition: width 0.3s ease;
}

/* QUESTION CARD */
.question-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  position: relative;
  transition: all 0.25s ease;
}

.question-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.badge-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.badge {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.badge-category {
  background: var(--secondary-light);
  color: var(--secondary);
}

.badge-num {
  background: var(--surface-alt);
  color: var(--text-main);
  border: 1px solid var(--border);
}

.btn-flag {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-flag:hover {
  background: var(--warning-light);
  color: var(--warning);
  border-color: var(--warning);
}

.btn-flag.active {
  background: var(--warning);
  color: white;
  border-color: var(--warning);
}

.question-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-main);
  line-height: 1.6;
}

/* OPTIONS LIST */
.options-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.option-item {
  background: var(--surface-alt);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  display: flex;
  align-items: flex-start;
  gap: 0.85rem;
  cursor: pointer;
  transition: all 0.2s ease;
  user-select: none;
}

.option-item:hover {
  border-color: var(--primary);
  background: var(--surface);
  transform: translateY(-1px);
}

.option-item.selected {
  border-color: var(--primary);
  background: var(--primary-light);
}

.option-letter {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--surface);
  border: 2px solid var(--border);
  color: var(--text-main);
  font-weight: 700;
  font-size: 0.85rem;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: all 0.2s ease;
}

.option-item.selected .option-letter {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
}

.option-text {
  font-size: 0.95rem;
  color: var(--text-main);
  line-height: 1.5;
  flex: 1;
}

/* OPTION STATES IN REVIEW/STUDY MODE */
.option-item.correct {
  border-color: var(--primary) !important;
  background: #dcfce7 !important;
}

.option-item.correct .option-letter {
  background: var(--primary) !important;
  border-color: var(--primary) !important;
  color: white !important;
}

.option-item.incorrect {
  border-color: var(--danger) !important;
  background: var(--danger-light) !important;
}

.option-item.incorrect .option-letter {
  background: var(--danger) !important;
  border-color: var(--danger) !important;
  color: white !important;
}

/* EXPLANATION BOX */
.explanation-box {
  background: var(--surface-alt);
  border-left: 4px solid var(--secondary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 1.15rem 1.25rem;
  margin-top: 0.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  animation: fadeIn 0.3s ease;
}

.explanation-header {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.explanation-content {
  font-size: 0.92rem;
  color: var(--text-main);
  line-height: 1.6;
}

.explanation-ref {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 0.25rem;
}

/* CARD NAVIGATION FOOTER */
.card-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 0.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  gap: 0.75rem;
  flex-wrap: wrap;
}

.card-nav-main {
  display: flex;
  gap: 0.75rem;
  align-items: center;
}

.card-nav-extra {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  flex-wrap: wrap;
}

.btn {
  padding: 0.65rem 1.25rem;
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  transition: all 0.2s ease;
  border: 1px solid transparent;
}

.btn-secondary {
  background: var(--surface-alt);
  border-color: var(--border);
  color: var(--text-main);
}

.btn-secondary:hover:not(:disabled) {
  background: var(--border);
}

.btn-primary {
  background: var(--primary);
  color: white;
  box-shadow: 0 2px 4px rgba(5, 150, 105, 0.2);
}

.btn-primary:hover:not(:disabled) {
  background: var(--primary-hover);
  box-shadow: 0 4px 8px rgba(5, 150, 105, 0.3);
}

.btn-submit {
  background: linear-gradient(135deg, var(--secondary) 0%, #3730a3 100%);
  color: white;
}

.btn-submit:hover {
  filter: brightness(1.1);
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* RIGHT COLUMN: QUESTION PALETTE */
.palette-container {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 1rem;
  height: fit-content;
  max-height: calc(100vh - 100px);
  position: sticky;
  top: 85px;
}

.palette-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.75rem;
}

.palette-title {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-main);
}

.palette-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.legend-dot.answered { background: var(--primary); }
.legend-dot.flagged { background: var(--warning); }
.legend-dot.unanswered { background: var(--surface-alt); border: 1px solid var(--border); }
.legend-dot.correct { background: var(--primary); }
.legend-dot.wrong { background: var(--danger); }

/* GRID 80 TILES */
.palette-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.45rem;
  overflow-y: auto;
  max-height: 480px;
  padding-right: 0.25rem;
}

.grid-btn {
  height: 38px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface-alt);
  color: var(--text-main);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  transition: all 0.15s ease;
}

.grid-btn:hover {
  border-color: var(--primary);
  transform: scale(1.05);
}

.grid-btn.current {
  border: 2px solid var(--secondary) !important;
  font-weight: 800;
}

.grid-btn.answered {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
}

.grid-btn.flagged {
  border-color: var(--warning) !important;
}

.grid-btn.flagged::after {
  content: '★';
  position: absolute;
  top: 1px;
  right: 2px;
  font-size: 0.6rem;
  color: var(--warning);
}

.grid-btn.answered.flagged::after {
  color: white;
}

/* RESULTS PALETTE STATES */
.grid-btn.result-correct {
  background: var(--primary) !important;
  border-color: var(--primary) !important;
  color: white !important;
}

.grid-btn.result-wrong {
  background: var(--danger) !important;
  border-color: var(--danger) !important;
  color: white !important;
}

.grid-btn.result-skipped {
  background: var(--surface-alt) !important;
  border: 2px dashed #94a3b8 !important;
  color: var(--text-muted) !important;
}

/* ==========================================
   TOPIC & FLASHCARD VIEW (Mobile First Overhaul)
   ========================================== */
.topic-container, .flashcard-container {
  display: flex;
  flex-direction: column;
  gap: 1.15rem;
  min-width: 0;
  max-width: 100%;
}

/* HORIZONTAL SWIPEABLE RIBBON */
.topic-ribbon-container {
  width: 100%;
  max-width: 100%;
  min-width: 0;
  overflow: hidden;
  position: relative;
}

.topic-selector-bar {
  display: flex;
  gap: 0.45rem;
  overflow-x: auto;
  white-space: nowrap;
  flex-wrap: nowrap;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
  padding: 0.25rem 0.15rem 0.5rem 0.15rem;
  scroll-behavior: smooth;
}

.topic-selector-bar::-webkit-scrollbar {
  display: none;
}

.topic-chip {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.45rem 0.85rem;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 600;
  white-space: nowrap;
  background: var(--surface);
  border: 1.5px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  user-select: none;
}

.topic-chip:hover {
  border-color: var(--secondary);
  color: var(--secondary);
}

.topic-chip:active {
  transform: scale(0.97);
}

.topic-chip .chip-count {
  background: var(--surface-alt);
  padding: 0.1rem 0.45rem;
  border-radius: var(--radius-full);
  font-size: 0.72rem;
  font-weight: 700;
  color: inherit;
}

.topic-chip.active {
  background: linear-gradient(135deg, var(--secondary) 0%, #1e40af 100%);
  border-color: var(--secondary);
  color: white;
  box-shadow: 0 4px 12px rgba(30, 58, 138, 0.25);
}

.topic-chip.active .chip-count {
  background: rgba(255, 255, 255, 0.25);
  color: white;
}

.topic-chip.chip-starred.active {
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  border-color: #d97706;
  color: white;
}

.topic-chip.chip-unmastered.active {
  background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
  border-color: #dc2626;
  color: white;
}

/* TOPIC DASHBOARD CARD */
.topic-dashboard {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1rem 1.15rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  box-shadow: var(--shadow-sm);
}

.topic-dash-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
}

.topic-dash-title {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--secondary);
  line-height: 1.2;
}

.topic-dash-sub {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.15rem;
  font-weight: 500;
}

.btn-topic-reset {
  background: transparent;
  border: 1px solid var(--border);
  padding: 0.35rem 0.65rem;
  border-radius: var(--radius-sm);
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  transition: all 0.15s ease;
  white-space: nowrap;
}

.btn-topic-reset:hover {
  border-color: var(--danger);
  color: var(--danger);
  background: var(--danger-light);
}

.topic-progress-track {
  height: 8px;
  background: var(--surface-alt);
  border-radius: var(--radius-full);
  overflow: hidden;
  position: relative;
}

.topic-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--secondary) 0%, var(--primary) 100%);
  border-radius: var(--radius-full);
  transition: width 0.35s ease;
}

.topic-stats-row {
  display: flex;
  justify-content: space-around;
  align-items: center;
  gap: 0.4rem;
  background: var(--surface-alt);
  padding: 0.55rem 0.65rem;
  border-radius: var(--radius-md);
}

.topic-stat-item {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.8rem;
  font-weight: 600;
  white-space: nowrap;
}

.topic-stat-item.correct { color: var(--primary); }
.topic-stat-item.wrong { color: var(--danger); }
.topic-stat-item.unanswered { color: var(--text-muted); }

.topic-stat-item .stat-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.topic-stat-item.correct .stat-dot { background: var(--primary); }
.topic-stat-item.wrong .stat-dot { background: var(--danger); }
.topic-stat-item.unanswered .stat-dot { background: #94a3b8; }

.topic-stat-item .stat-val {
  font-weight: 700;
  font-size: 0.92rem;
  color: inherit;
}

.topic-stat-item .stat-lbl {
  font-size: 0.75rem;
  color: inherit;
  opacity: 0.85;
}

/* TOPIC CONTROLS & FILTER PILLS */
.topic-controls-bar {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
  margin-top: 0.2rem;
}

.topic-filter-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
}

.topic-pill {
  padding: 0.32rem 0.68rem;
  border-radius: var(--radius-full);
  font-size: 0.76rem;
  font-weight: 600;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  color: var(--text-main);
  cursor: pointer;
  transition: all 0.15s ease;
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.topic-pill:hover {
  border-color: var(--secondary);
}

.topic-pill.active {
  background: var(--secondary);
  color: white;
  border-color: var(--secondary);
}

.topic-pill.pill-wrong.active {
  background: var(--danger);
  color: white;
  border-color: var(--danger);
}

.topic-pill.pill-correct.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.topic-search-wrap {
  position: relative;
  width: 100%;
  display: flex;
  align-items: center;
}

.topic-search-wrap .search-icon {
  position: absolute;
  left: 0.85rem;
  font-size: 0.92rem;
  pointer-events: none;
  opacity: 0.6;
}

.topic-search-input {
  width: 100%;
  padding: 0.48rem 2rem 0.48rem 2.2rem;
  border-radius: var(--radius-full);
  border: 1.5px solid var(--border);
  background: var(--surface-alt);
  color: var(--text-main);
  font-size: 0.86rem;
  outline: none;
  transition: all 0.2s ease;
  font-family: inherit;
}

.topic-search-input:focus {
  border-color: var(--secondary);
  background: var(--surface);
}

.search-clear-btn {
  position: absolute;
  right: 0.65rem;
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 0.85rem;
  padding: 0.2rem;
}

/* TOPIC QUESTIONS LIST */
.topic-questions-container {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.topic-question-card {
  padding: 1.15rem;
  transition: border-color 0.2s ease;
}

.study-badge-tag {
  font-size: 0.72rem;
  font-weight: 700;
  padding: 0.18rem 0.55rem;
  border-radius: var(--radius-sm);
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.study-badge-tag.correct {
  background: var(--primary-light);
  color: var(--primary);
}

.study-badge-tag.wrong {
  background: var(--danger-light);
  color: var(--danger);
}

.study-badge-tag.unanswered {
  background: var(--surface-alt);
  color: var(--text-muted);
  border: 1px dashed var(--border);
}

.topic-load-more-wrap {
  margin-top: 0.5rem;
}

.btn-load-more {
  width: 100%;
  padding: 0.85rem 1.25rem;
  font-weight: 700;
  font-size: 0.92rem;
  border-radius: var(--radius-md);
  background: var(--surface);
  border: 1.5px solid var(--secondary);
  color: var(--secondary);
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-load-more:hover {
  background: var(--secondary-light);
}

.topic-empty-card {
  padding: 2.5rem 1.5rem;
  text-align: center;
  background: var(--surface);
  border-radius: var(--radius-lg);
  border: 1px dashed var(--border);
}

/* COMMON SEARCH BAR (Used in Flashcards & Search) */
.search-bar {
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-full);
  padding: 0.45rem 1rem;
  display: flex;
  align-items: center;
  gap: 0.65rem;
  transition: all 0.2s ease;
  width: 100%;
}

.search-bar:focus-within {
  border-color: var(--secondary);
  box-shadow: 0 0 0 3px rgba(30, 58, 138, 0.1);
}

.search-input {
  border: none !important;
  background: transparent !important;
  color: var(--text-main);
  font-size: 0.88rem;
  width: 100%;
  outline: none !important;
  font-family: inherit;
  padding: 0;
}

/* ==========================================
   FLASHCARD / CÂU HỎI TỦ (3D Flip & Quick Mode)
   ========================================== */
.fc-header-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 0.85rem 1.15rem;
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
  box-shadow: var(--shadow-sm);
}

.fc-header-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.fc-mode-switcher {
  display: inline-flex;
  background: var(--surface-alt);
  padding: 0.25rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--border);
}

.fc-mode-btn {
  padding: 0.35rem 0.85rem;
  border-radius: var(--radius-full);
  border: none;
  background: transparent;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.2s ease;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.fc-mode-btn.active {
  background: var(--surface);
  color: var(--secondary);
  box-shadow: var(--shadow-sm);
}

.fc-mastery-badge {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-main);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.fc-mastery-track {
  height: 6px;
  background: var(--surface-alt);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.fc-mastery-fill {
  height: 100%;
  background: linear-gradient(90deg, #10b981 0%, #059669 100%);
  border-radius: var(--radius-full);
  transition: width 0.35s ease;
}

/* 3D INTERACTIVE FLIP CARD */
.fc-scene-wrapper {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.95rem;
  width: 100%;
  max-width: 600px;
  margin: 0 auto;
}

.fc-3d-scene {
  perspective: 1200px;
  width: 100%;
  min-height: 290px;
  cursor: pointer;
  user-select: none;
}

.fc-card {
  position: relative;
  width: 100%;
  min-height: 290px;
  transform-style: preserve-3d;
  transition: transform 0.45s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: var(--radius-lg);
}

.fc-card.flipped {
  transform: rotateY(180deg);
}

.fc-card-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: var(--radius-lg);
  border: 2px solid var(--border);
  background: var(--surface);
  padding: 1.25rem 1.35rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 1rem;
  box-shadow: var(--shadow-md);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.fc-face-front {
  background: var(--surface);
  border-color: rgba(30, 58, 138, 0.2);
}

.fc-face-back {
  transform: rotateY(180deg);
  background: var(--surface);
  border-color: var(--primary);
}

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

.fc-topic-tag {
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--secondary);
  background: var(--secondary-light);
  padding: 0.22rem 0.65rem;
  border-radius: var(--radius-full);
}

.fc-topic-tag.back-tag {
  color: var(--primary);
  background: var(--primary-light);
}

.fc-face-actions {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.fc-icon-btn {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--surface-alt);
  font-size: 0.95rem;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.15s ease;
}

.fc-icon-btn:hover {
  transform: scale(1.08);
  border-color: var(--secondary);
}

.fc-icon-btn.starred {
  background: #fef3c7;
  border-color: #f59e0b;
  color: #d97706;
}

.fc-q-content {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  margin: auto 0;
}

.fc-q-label {
  font-size: 0.76rem;
  font-weight: 700;
  color: var(--text-muted);
  letter-spacing: 0.03em;
}

.fc-q-text {
  font-size: 1.12rem;
  font-weight: 700;
  line-height: 1.5;
  color: var(--text-main);
  font-family: var(--font-heading);
}

.fc-a-content {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin: auto 0;
}

.fc-a-text {
  font-size: 1.02rem;
  font-weight: 500;
  line-height: 1.6;
  color: #047857;
  background: var(--primary-light);
  padding: 0.85rem 1rem;
  border-radius: var(--radius-md);
  border-left: 4px solid var(--primary);
}

[data-theme="dark"] .fc-a-text {
  color: #a7f3d0;
  background: rgba(5, 150, 105, 0.15);
}

.fc-face-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.74rem;
  color: var(--text-muted);
  font-weight: 500;
  border-top: 1px solid var(--border);
  padding-top: 0.65rem;
}

.fc-hint-text {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-style: italic;
}

.fc-pos-badge {
  font-weight: 700;
  background: var(--surface-alt);
  padding: 0.18rem 0.5rem;
  border-radius: var(--radius-full);
}

.fc-status-pill {
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: 0.72rem;
  background: var(--surface-alt);
  color: var(--text-muted);
}

.fc-status-pill.mastered {
  background: var(--primary-light);
  color: var(--primary);
}

/* THUMB-FRIENDLY BOTTOM CONTROLS FOR FLASHCARD */
.fc-dock-controls {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}

.fc-quick-actions {
  display: flex;
  gap: 0.5rem;
  width: 100%;
}

.fc-btn-flip {
  flex: 2;
  height: 46px;
  font-weight: 700;
  font-size: 0.95rem;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--secondary) 0%, #1e40af 100%);
  color: white;
  border: none;
  box-shadow: 0 4px 12px rgba(30, 58, 138, 0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  cursor: pointer;
}

.fc-btn-flip:active {
  transform: scale(0.98);
}

.fc-btn-shuffle {
  flex: 1;
  height: 46px;
  font-size: 0.88rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  cursor: pointer;
}

.fc-nav-dock {
  display: grid;
  grid-template-columns: 1fr 1.25fr 1.25fr 1fr;
  gap: 0.45rem;
  width: 100%;
}

.fc-nav-btn {
  height: 48px;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--border);
  background: var(--surface);
  color: var(--text-main);
  font-weight: 700;
  font-size: 0.88rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.25rem;
  transition: all 0.15s ease;
}

.fc-nav-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.fc-nav-btn:not(:disabled):active {
  transform: scale(0.96);
  background: var(--surface-alt);
}

.fc-rate-btn {
  height: 48px;
  border-radius: var(--radius-md);
  font-weight: 700;
  font-size: 0.86rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.25rem;
  transition: all 0.15s ease;
}

.fc-rate-btn.unmastered {
  background: var(--surface);
  border: 1.5px solid #f87171;
  color: #dc2626;
}

.fc-rate-btn.unmastered:active {
  transform: scale(0.96);
  background: #fee2e2;
}

.fc-rate-btn.mastered {
  background: linear-gradient(135deg, #10b981 0%, #059669 100%);
  border: none;
  color: white;
  box-shadow: 0 3px 10px rgba(16, 185, 129, 0.25);
}

.fc-rate-btn.mastered:active {
  transform: scale(0.96);
}

/* QUICK LIST MODE */
.flashcard-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
  gap: 1rem;
}

.recall-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.15rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
  transition: all 0.2s ease;
}

.recall-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--primary);
}

.recall-card.card-mastered {
  border-left: 4px solid var(--primary);
}

.recall-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
}

.recall-topic {
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--secondary);
  text-transform: uppercase;
}

.recall-actions {
  display: flex;
  gap: 0.35rem;
  align-items: center;
}

.recall-q {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-main);
  line-height: 1.5;
}

.recall-a {
  font-size: 0.9rem;
  color: #047857;
  background: var(--primary-light);
  padding: 0.65rem 0.85rem;
  border-radius: var(--radius-sm);
  line-height: 1.5;
  display: none;
}

.recall-a.show {
  display: block;
}

[data-theme="dark"] .recall-a {
  color: #6ee7b7;
  background: rgba(5, 150, 105, 0.15);
}

.btn-toggle-answer {
  align-self: flex-start;
  padding: 0.3rem 0.65rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface-alt);
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-toggle-answer:hover {
  background: var(--secondary-light);
}

/* RESULTS MODAL */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 1rem;
  animation: fadeIn 0.2s ease;
}

.modal-overlay.active {
  display: flex;
}

.modal-card {
  background: var(--surface);
  border-radius: var(--radius-lg);
  max-width: 560px;
  width: 100%;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
  padding: 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 1.25rem;
}

.score-badge {
  width: 110px;
  height: 110px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: white;
  box-shadow: 0 8px 20px rgba(5, 150, 105, 0.3);
}

.score-num {
  font-size: 2.2rem;
  font-weight: 800;
  font-family: var(--font-heading);
  line-height: 1;
}

.score-total {
  font-size: 0.85rem;
  opacity: 0.9;
}

.result-title {
  font-family: var(--font-heading);
  font-size: 1.45rem;
  font-weight: 700;
  color: var(--text-main);
}

.result-summary-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.75rem;
  width: 100%;
}

.summary-box {
  background: var(--surface-alt);
  padding: 0.75rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
}

.summary-box .val {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
}

.summary-box .lbl {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.modal-actions {
  display: flex;
  gap: 0.75rem;
  width: 100%;
}

.modal-actions .btn {
  flex: 1;
}

/* KEYBOARD SHORTCUTS HINT */
.shortcuts-hint {
  font-size: 0.75rem;
  color: var(--text-light);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  margin-top: 0.5rem;
}

.kbd {
  background: var(--surface-alt);
  border: 1px solid var(--border);
  padding: 0.1rem 0.35rem;
  border-radius: var(--radius-sm);
  font-family: monospace;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* DESKTOP LAYOUT OVERRIDES (>= 1025px) */
@media (min-width: 1025px) {
  .header-top-row {
    display: contents;
  }
  .card-nav-main {
    display: contents;
  }
}

/* MOBILE BOTTOM DOCK & DRAWER BASE STYLES */
.mobile-exam-dock {
  display: none;
}

.mobile-palette-backdrop {
  display: none;
}

.btn-palette-close {
  display: none;
}

/* TABLET & SMALL LAPTOPS (<= 1024px) */
@media (max-width: 1024px) {
  header.app-header {
    position: sticky;
    top: 0;
  }

  .header-container {
    flex-direction: column;
    padding: 0.5rem 1rem;
    gap: 0.4rem;
  }

  .header-top-row {
    width: 100%;
    justify-content: space-between;
  }

  .nav-tabs {
    width: 100%;
  }

  main.app-main {
    grid-template-columns: 1fr;
    padding: 1rem;
    gap: 1rem;
    min-width: 0;
    max-width: 100%;
  }

  .palette-container {
    position: static;
    max-height: none;
  }

  .palette-grid {
    grid-template-columns: repeat(10, 1fr);
    max-height: 240px;
  }

  /* Drawer Bottom Sheet for Palette on Mobile */
  .btn-palette-close {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--surface-alt);
    border: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 700;
    cursor: pointer;
  }

  .mobile-palette-backdrop.active {
    display: block;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.55);
    backdrop-filter: blur(3px);
    z-index: 1050;
    animation: fadeIn 0.2s ease;
  }

  .palette-container.mobile-open {
    display: flex !important;
    position: fixed !important;
    bottom: 0 !important;
    left: 0 !important;
    right: 0 !important;
    top: auto !important;
    z-index: 1100 !important;
    border-radius: 20px 20px 0 0 !important;
    box-shadow: 0 -8px 30px rgba(0, 0, 0, 0.3) !important;
    max-height: 82vh !important;
    overflow-y: auto !important;
    border: 1px solid var(--border) !important;
    border-bottom: none !important;
    background: var(--surface) !important;
    animation: slideUpSheet 0.28s cubic-bezier(0.16, 1, 0.3, 1) !important;
    padding-bottom: calc(1rem + env(safe-area-inset-bottom, 0px)) !important;
  }

  .palette-container.mobile-open .palette-grid {
    grid-template-columns: repeat(8, 1fr) !important;
    max-height: 55vh !important;
  }

  @keyframes slideUpSheet {
    from { transform: translateY(100%); }
    to { transform: translateY(0); }
  }
}

/* SMARTPHONES & SMALL TABLETS (<= 768px) */
@media (max-width: 768px) {
  .header-container {
    padding: 0.45rem 0.65rem;
    gap: 0.35rem;
  }

  .brand-section {
    gap: 0.45rem;
    min-width: 0;
  }

  .brand-logo {
    width: 32px;
    height: 32px;
    font-size: 1.05rem;
    border-radius: var(--radius-sm);
  }

  .brand-titles h1 {
    font-size: 0.92rem;
    letter-spacing: -0.01em;
  }

  .brand-titles .subtitle {
    display: none;
  }

  .header-actions {
    gap: 0.35rem;
    flex-shrink: 0;
  }

  .timer-badge {
    padding: 0.25rem 0.5rem;
    font-size: 0.88rem;
    gap: 0.25rem;
  }

  .btn-timer-action {
    padding: 0.25rem 0.55rem;
    font-size: 0.78rem;
    height: 32px;
  }

  .btn-icon {
    width: 32px;
    height: 32px;
    font-size: 0.95rem;
  }

  .tab-btn {
    padding: 0.35rem 0.75rem;
    font-size: 0.78rem;
    gap: 0.25rem;
  }

  main.app-main {
    padding: 0.65rem 0.75rem 85px 0.75rem; /* bottom padding for mobile dock */
  }

  /* Sticky Bottom Exam Dock */
  .mobile-exam-dock {
    display: flex;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 950;
    background: var(--surface);
    border-top: 1px solid var(--border);
    padding: 0.5rem 0.75rem calc(0.5rem + env(safe-area-inset-bottom, 0px));
    box-shadow: 0 -4px 18px rgba(0, 0, 0, 0.09);
    align-items: center;
    gap: 0.5rem;
    backdrop-filter: blur(12px);
  }

  .dock-nav-btn {
    height: 44px;
    padding: 0 0.95rem;
    border-radius: var(--radius-md);
    background: var(--surface-alt);
    border: 1px solid var(--border);
    color: var(--text-main);
    font-weight: 700;
    font-size: 0.88rem;
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    cursor: pointer;
    transition: all 0.15s ease;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
  }

  .dock-nav-btn:active {
    transform: scale(0.96);
    background: var(--border);
  }

  .dock-nav-btn:disabled {
    opacity: 0.35;
    cursor: not-allowed;
    transform: none;
  }

  .dock-palette-trigger {
    flex: 1;
    height: 44px;
    background: linear-gradient(135deg, var(--secondary-light) 0%, rgba(79, 70, 229, 0.08) 100%);
    border: 1.5px solid var(--secondary);
    border-radius: var(--radius-md);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
    transition: all 0.15s ease;
  }

  .dock-palette-trigger:active {
    transform: scale(0.98);
    background: var(--secondary);
    color: white !important;
  }

  .dock-palette-trigger:active .dock-q-num,
  .dock-palette-trigger:active .dock-q-sub {
    color: white !important;
  }

  .dock-q-num {
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 0.88rem;
    color: var(--secondary);
    line-height: 1.1;
  }

  .dock-q-sub {
    font-size: 0.68rem;
    font-weight: 600;
    color: var(--text-muted);
  }

  /* Card Navigation inside question card on mobile */
  .card-nav {
    flex-direction: column;
    gap: 0.6rem;
  }

  .card-nav-main {
    display: flex;
    gap: 0.5rem;
    width: 100%;
  }

  .card-nav-main .nav-btn-prev,
  .card-nav-main .nav-btn-next {
    flex: 1;
    height: 46px;
    font-size: 0.95rem;
    font-weight: 700;
    border-radius: var(--radius-md);
  }

  .card-nav-extra {
    display: flex;
    gap: 0.5rem;
    width: 100%;
  }

  .card-nav-extra .btn {
    flex: 1;
    padding: 0.55rem 0.75rem;
    font-size: 0.82rem;
  }

  /* Hide desktop keyboard shortcuts on mobile */
  .shortcuts-hint {
    display: none !important;
  }

  /* Flashcards grid */
  .flashcard-list {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }

  /* Topic study scrollable chips */
  .topic-selector-bar {
    overflow-x: auto;
    white-space: nowrap;
    flex-wrap: nowrap;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
    padding: 0.5rem 0.75rem;
  }

  .topic-selector-bar::-webkit-scrollbar {
    display: none;
  }

  .topic-chip {
    flex-shrink: 0;
    padding: 0.35rem 0.75rem;
    font-size: 0.78rem;
  }
}

/* SMARTPHONES & COMPACT SCREENS (<= 480px) */
@media (max-width: 480px) {
  .header-container {
    padding: 0.45rem 0.65rem;
    gap: 0.35rem;
  }

  .brand-logo {
    width: 32px;
    height: 32px;
    font-size: 1.05rem;
    border-radius: var(--radius-sm);
  }

  .brand-titles h1 {
    font-size: 0.95rem;
    letter-spacing: -0.01em;
  }

  .brand-titles .subtitle {
    display: none; /* Hide subtitle on very small screens for ultra-compact header */
  }

  .header-actions {
    gap: 0.4rem;
  }

  .timer-badge {
    padding: 0.25rem 0.55rem;
    font-size: 0.92rem;
    gap: 0.3rem;
  }

  .btn-timer-action {
    padding: 0.25rem 0.6rem;
    font-size: 0.76rem;
    height: 32px;
  }

  .btn-icon {
    width: 32px;
    height: 32px;
    font-size: 0.95rem;
  }

  .tab-btn {
    padding: 0.35rem 0.75rem;
    font-size: 0.78rem;
    gap: 0.25rem;
  }

  .question-card {
    padding: 1rem 0.85rem;
    border-radius: var(--radius-md);
    gap: 0.85rem;
  }

  .question-meta {
    gap: 0.35rem;
  }

  .badge {
    font-size: 0.68rem;
    padding: 0.2rem 0.5rem;
  }

  .btn-flag {
    padding: 0.25rem 0.5rem;
    font-size: 0.72rem;
  }

  .question-title {
    font-size: 1rem;
    line-height: 1.5;
  }

  .options-list {
    gap: 0.55rem;
  }

  .option-item {
    padding: 0.75rem 0.8rem;
    gap: 0.65rem;
    border-radius: var(--radius-md);
    min-height: 48px;
  }

  .option-letter {
    width: 28px;
    height: 28px;
    font-size: 0.8rem;
  }

  .option-text {
    font-size: 0.88rem;
    line-height: 1.45;
  }

  .explanation-box {
    padding: 0.85rem;
    gap: 0.4rem;
  }

  .explanation-header {
    font-size: 0.78rem;
  }

  .explanation-content {
    font-size: 0.85rem;
    line-height: 1.5;
  }

  .palette-container.mobile-open .palette-grid {
    grid-template-columns: repeat(6, 1fr) !important;
  }

  .grid-btn {
    height: 34px;
    font-size: 0.8rem;
  }

  /* History list & stats on small screens */
  .history-stats-banner {
    grid-template-columns: repeat(2, 1fr);
    padding: 0.65rem;
    gap: 0.4rem;
  }

  .stat-item {
    padding: 0.3rem;
  }

  .stat-item .stat-label {
    font-size: 0.65rem;
  }

  .stat-item .stat-val {
    font-size: 1.2rem;
  }

  .stat-item .stat-sub {
    font-size: 0.65rem;
  }

  .history-toolbar {
    flex-direction: column;
    align-items: stretch;
    gap: 0.4rem;
  }

  .history-toolbar button {
    width: 100%;
  }

  .history-card {
    padding: 0.8rem;
    gap: 0.65rem;
  }

  .history-card-header {
    flex-wrap: wrap;
    gap: 0.35rem;
  }

  .history-score-main {
    font-size: 1.6rem;
  }

  .history-breakdown-row {
    gap: 0.4rem;
    font-size: 0.75rem;
  }

  .history-actions-col {
    width: 100%;
    margin-top: 0.4rem;
  }

  .history-actions-col .btn {
    flex: 1;
  }

  .review-sticky-header {
    top: 80px;
    padding: 0.6rem;
    border-radius: var(--radius-sm);
  }

  .review-filter-row {
    overflow-x: auto;
    white-space: nowrap;
    flex-wrap: nowrap;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
    padding-bottom: 2px;
  }

  .review-filter-row::-webkit-scrollbar {
    display: none;
  }

  .review-pill {
    flex-shrink: 0;
    padding: 0.28rem 0.6rem;
    font-size: 0.74rem;
  }

  .review-question-card {
    padding: 0.85rem;
    gap: 0.6rem;
  }

  .review-opt-item {
    padding: 0.55rem 0.7rem;
    font-size: 0.82rem;
    gap: 0.5rem;
  }

  .review-badge-tag {
    font-size: 0.68rem;
    padding: 0.12rem 0.4rem;
  }

  /* Modal on small screens */
  .modal-overlay {
    padding: 0.5rem;
  }

  .modal-card {
    padding: 1.25rem 0.85rem;
    gap: 0.75rem;
    max-height: 92vh;
  }

  .score-badge {
    width: 80px;
    height: 80px;
  }

  .score-num {
    font-size: 1.7rem;
  }

  .result-title {
    font-size: 1.15rem;
  }

  .result-summary-grid {
    grid-template-columns: repeat(3, 1fr) !important;
    gap: 0.25rem;
  }

  .summary-box {
    padding: 0.4rem 0.2rem;
  }

  .summary-box .val {
    font-size: 0.95rem;
  }

  .summary-box .lbl {
    font-size: 0.65rem;
  }

  .modal-actions {
    flex-direction: column;
    gap: 0.35rem;
  }

  /* Topic Dashboard on mobile phones */
  .topic-dashboard {
    padding: 0.85rem 0.75rem;
    gap: 0.65rem;
  }

  .topic-dash-title {
    font-size: 1rem;
  }

  .topic-stats-row {
    padding: 0.45rem 0.6rem;
    gap: 0.35rem;
  }

  .topic-stat-item .stat-val {
    font-size: 0.88rem;
  }

  .topic-stat-item .stat-lbl {
    font-size: 0.7rem;
  }

  .topic-filter-pills {
    gap: 0.3rem;
  }

  .topic-pill {
    font-size: 0.72rem;
    padding: 0.28rem 0.55rem;
  }

  .topic-search-input {
    font-size: 0.82rem;
    padding: 0.45rem 1.8rem 0.45rem 2rem;
  }

  /* Flashcards on mobile phones */
  .fc-header-card {
    padding: 0.75rem;
    gap: 0.5rem;
  }

  .fc-mode-btn {
    padding: 0.28rem 0.65rem;
    font-size: 0.76rem;
  }

  .fc-mastery-badge {
    font-size: 0.74rem;
  }

  .fc-3d-scene {
    min-height: 270px;
  }

  .fc-card {
    min-height: 270px;
  }

  .fc-card-face {
    padding: 1rem 0.85rem;
    gap: 0.75rem;
  }

  .fc-q-text {
    font-size: 1rem;
    line-height: 1.45;
  }

  .fc-a-text {
    font-size: 0.92rem;
    padding: 0.75rem 0.85rem;
    line-height: 1.5;
  }

  .fc-nav-dock {
    gap: 0.35rem;
  }

  .fc-nav-btn, .fc-rate-btn {
    height: 44px;
    font-size: 0.8rem;
    padding: 0 0.25rem;
  }

  .fc-btn-flip, .fc-btn-shuffle {
    height: 44px;
    font-size: 0.85rem;
  }

  .flashcard-list {
    grid-template-columns: 1fr;
    gap: 0.65rem;
  }

  .recall-card {
    padding: 0.85rem;
    gap: 0.55rem;
  }
}

/* ==========================================
   EXAM HISTORY & DETAILED REVIEW STYLES
   ========================================== */
.history-container {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  animation: fadeIn 0.25s ease-out;
}

.history-stats-banner {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 1rem;
}

.stat-item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 0.5rem;
  border-radius: var(--radius-sm);
}

.stat-item .stat-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  font-weight: 600;
}

.stat-item .stat-val {
  font-family: var(--font-heading);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.2;
}

.stat-item .stat-sub {
  font-size: 0.75rem;
  color: var(--text-light);
}

.history-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.history-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.history-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
  transition: all 0.2s ease;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.history-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--secondary);
}

.history-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}

.history-card-title {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  font-size: 0.95rem;
}

.history-date {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.history-card-body {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 1.25rem;
}

@media (max-width: 768px) {
  .history-card-body {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }
}

.history-score-col {
  display: flex;
  align-items: baseline;
  gap: 0.35rem;
}

.history-score-main {
  font-family: var(--font-heading);
  font-size: 2.2rem;
  font-weight: 800;
  line-height: 1;
}

.history-score-sub {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

.history-meta-col {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.history-breakdown-row {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  font-size: 0.85rem;
}

.breakdown-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-weight: 500;
}

.breakdown-tag.correct { color: var(--primary); }
.breakdown-tag.wrong { color: var(--danger); }
.breakdown-tag.skipped { color: var(--text-muted); }
.breakdown-tag.time { color: var(--accent); }

.history-bar-track {
  height: 6px;
  background: var(--surface-alt);
  border-radius: var(--radius-full);
  overflow: hidden;
  display: flex;
}

.history-bar-seg.correct { background: var(--primary); }
.history-bar-seg.wrong { background: var(--danger); }
.history-bar-seg.skipped { background: var(--border); }

.history-actions-col {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

.history-empty-state {
  text-align: center;
  padding: 3.5rem 1.5rem;
  background: var(--surface);
  border: 1px dashed var(--border);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.history-empty-icon {
  font-size: 3rem;
  line-height: 1;
}

/* REVIEW DETAIL STYLES */
.review-view-container {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  animation: fadeIn 0.25s ease-out;
}

.review-sticky-header {
  position: sticky;
  top: 60px;
  z-index: 40;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 0.85rem 1.25rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.review-top-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.review-filter-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.review-pill {
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 600;
  border: 1px solid var(--border);
  background: var(--surface-alt);
  color: var(--text-main);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  transition: all 0.15s ease;
}

.review-pill:hover {
  border-color: var(--secondary);
}

.review-pill.active {
  background: var(--secondary);
  color: white;
  border-color: var(--secondary);
}

.review-pill.pill-wrong.active {
  background: var(--danger);
  border-color: var(--danger);
  color: white;
}

.review-pill.pill-correct.active {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
}

.review-pill .count {
  background: rgba(0, 0, 0, 0.1);
  padding: 0.1rem 0.35rem;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
}

.review-pill.active .count {
  background: rgba(255, 255, 255, 0.25);
}

.review-question-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  scroll-margin-top: 180px;
}

.review-question-card.status-correct {
  border-left: 5px solid var(--primary);
}

.review-question-card.status-wrong {
  border-left: 5px solid var(--danger);
}

.review-question-card.status-skipped {
  border-left: 5px solid var(--warning);
}

.review-q-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.review-opt-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.review-opt-item {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--border);
  background: var(--surface-alt);
  font-size: 0.92rem;
  transition: all 0.15s ease;
}

.review-opt-item.opt-correct {
  background: rgba(5, 150, 105, 0.08);
  border-color: var(--primary);
  color: var(--text-main);
  font-weight: 500;
}

.review-opt-item.opt-user-wrong {
  background: rgba(239, 68, 68, 0.08);
  border-color: var(--danger);
  color: var(--text-main);
}

.review-badge-tag {
  margin-left: auto;
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm);
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.review-badge-tag.correct {
  background: var(--primary-light);
  color: var(--primary);
}

.review-badge-tag.wrong {
  background: var(--danger-light);
  color: var(--danger);
}

.review-badge-tag.skipped {
  background: var(--warning-light);
  color: var(--warning);
}

.review-explanation-box {
  margin-top: 0.5rem;
  padding: 0.85rem 1rem;
  background: var(--surface-alt);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.review-explanation-box .exp-title {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-weight: 700;
  font-size: 0.85rem;
  color: var(--secondary);
}

.review-explanation-box .exp-text {
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--text-main);
}

.review-explanation-box .exp-ref {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-style: italic;
  display: flex;
  align-items: center;
  gap: 0.3rem;
}