/* ==========================================================================
   GRE Big Book Sentence Completion Trainer - Modern Responsive Stylesheet
   ========================================================================== */

:root {
  --font-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  /* Color Palette - Light Theme */
  --bg-app: #f8fafc;
  --bg-card: #ffffff;
  --bg-surface: #f1f5f9;
  --bg-surface-hover: #e2e8f0;
  --border-color: #e2e8f0;
  --border-subtle: #cbd5e1;

  --text-main: #0f172a;
  --text-muted: #475569;
  --text-dim: #64748b;

  --primary: #4338ca;
  --primary-hover: #3730a3;
  --primary-light: #e0e7ff;
  --primary-text: #312e81;

  --accent-google: #1a73e8;
  --accent-google-hover: #1557b0;
  --accent-google-bg: #e8f0fe;

  --green-main: #16a34a;
  --green-bg: #dcfce7;
  --green-border: #86efac;
  --green-text: #14532d;

  --red-main: #dc2626;
  --red-bg: #fee2e2;
  --red-border: #fca5a5;
  --red-text: #7f1d1d;

  --amber-main: #d97706;
  --amber-bg: #fef3c7;
  --amber-border: #fde68a;
  --amber-text: #78350f;

  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.07), 0 2px 4px -2px rgb(0 0 0 / 0.07);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.08), 0 4px 6px -4px rgb(0 0 0 / 0.08);

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
}

body.dark-theme {
  --bg-app: #0b0f19;
  --bg-card: #151c2c;
  --bg-surface: #1e293b;
  --bg-surface-hover: #334155;
  --border-color: #273549;
  --border-subtle: #37475d;

  --text-main: #f8fafc;
  --text-muted: #cbd5e1;
  --text-dim: #94a3b8;

  --primary: #6366f1;
  --primary-hover: #4f46e5;
  --primary-light: #312e81;
  --primary-text: #e0e7ff;

  --accent-google: #4285f4;
  --accent-google-hover: #1a73e8;
  --accent-google-bg: #172b4d;

  --green-main: #22c55e;
  --green-bg: #064e3b;
  --green-border: #059669;
  --green-text: #dcfce7;

  --red-main: #ef4444;
  --red-bg: #450a0a;
  --red-border: #b91c1c;
  --red-text: #fee2e2;

  --amber-main: #f59e0b;
  --amber-bg: #451a03;
  --amber-border: #b45309;
  --amber-text: #fef3c7;

  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.4);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.5);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.6);
}

/* ==========================================================================
   Base & Reset
   ========================================================================== */

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

html, body {
  min-height: 100%;
  font-family: var(--font-sans);
  background-color: var(--bg-app);
  color: var(--text-main);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

button, input, select {
  font-family: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

/* ==========================================================================
   Header
   ========================================================================== */

.app-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(8px);
}

.header-inner {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0.75rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand-group {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.brand-badge {
  background: linear-gradient(135deg, var(--primary), #7c3aed);
  color: #fff;
  font-weight: 800;
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  padding: 0.4rem 0.65rem;
  border-radius: var(--radius-sm);
  text-transform: uppercase;
}

.brand-titles h1 {
  font-size: 1.15rem;
  font-weight: 800;
  line-height: 1.2;
}

.brand-titles h1 span {
  color: var(--primary);
}

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

.header-controls {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  flex-wrap: wrap;
}

.select-wrapper {
  position: relative;
}

.custom-select {
  appearance: none;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  padding: 0.45rem 2rem 0.45rem 0.75rem;
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  color: var(--text-main);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.6rem center;
  transition: var(--transition-fast);
}

.custom-select:hover, .custom-select:focus {
  border-color: var(--primary);
  outline: none;
}

.mode-toggle-group {
  display: flex;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 2px;
}

.toggle-btn {
  padding: 0.35rem 0.75rem;
  font-size: 0.8rem;
  font-weight: 600;
  border-radius: calc(var(--radius-sm) - 2px);
  color: var(--text-dim);
  transition: var(--transition-fast);
}

.toggle-btn.active {
  background-color: var(--bg-card);
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

.icon-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  transition: var(--transition-fast);
}

.icon-btn:hover {
  background-color: var(--bg-surface-hover);
  color: var(--text-main);
}

.sun-icon { display: block; }
.moon-icon { display: none; }
body.dark-theme .sun-icon { display: none; }
body.dark-theme .moon-icon { display: block; }

/* ==========================================================================
   Layout & Container
   ========================================================================== */

.app-container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 1.25rem;
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 1.5rem;
  align-items: start;
}

/* ==========================================================================
   Stats Bar
   ========================================================================== */

.stats-bar {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.65rem 1rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 1.25rem;
  box-shadow: var(--shadow-sm);
  flex-wrap: wrap;
}

.stat-badge {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.stat-val {
  font-weight: 700;
  color: var(--text-main);
  font-family: var(--font-mono);
}

.stat-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
}
.stat-dot.green { background-color: var(--green-main); }
.stat-dot.red { background-color: var(--red-main); }

.stats-actions {
  margin-left: auto;
}

.subtle-btn {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-dim);
  padding: 0.3rem 0.6rem;
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
}
.subtle-btn:hover {
  color: var(--red-main);
  background: var(--red-bg);
}

/* ==========================================================================
   Question Card
   ========================================================================== */

.question-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

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

.question-badges {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.pill {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.3rem 0.65rem;
  border-radius: var(--radius-full);
  letter-spacing: 0.02em;
}

.pill-primary {
  background-color: var(--primary-light);
  color: var(--primary-text);
}

.pill-secondary {
  background-color: var(--bg-surface);
  color: var(--text-muted);
  border: 1px solid var(--border-color);
}

.pill-neutral {
  background-color: var(--bg-surface);
  color: var(--text-main);
  font-weight: 800;
}

.pill-diff {
  background-color: var(--amber-bg);
  color: var(--amber-text);
  border: 1px solid var(--amber-border);
}

.pill-recap {
  background-color: var(--red-bg);
  color: var(--red-text);
  border: 1px solid var(--red-border);
  font-weight: 800;
}

/* Header Mistakes Button */
.recap-header-btn {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.4rem 0.8rem;
  background-color: var(--red-bg);
  color: var(--red-text);
  border: 1.5px solid var(--red-border);
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition-fast);
}

.recap-header-btn:hover {
  background-color: var(--red-main);
  color: #fff;
  border-color: var(--red-main);
}

.recap-header-btn.active {
  background-color: var(--red-main);
  color: #fff;
  border-color: var(--red-main);
  box-shadow: 0 0 0 2px rgba(220, 38, 38, 0.35);
}

.recap-counter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.1rem 0.45rem;
  font-size: 0.72rem;
  font-weight: 800;
  border-radius: var(--radius-full);
  background-color: #fff;
  color: var(--red-main);
}

.recap-header-btn.active .recap-counter {
  background-color: #fff;
  color: var(--red-main);
}

/* Mistake Notice in Feedback */
.mistake-save-notice {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 0.95rem;
  border-radius: var(--radius-sm);
  background-color: var(--red-bg);
  color: var(--red-text);
  border: 1px solid var(--red-border);
  font-size: 0.82rem;
  font-weight: 600;
}

/* Drawer Recap Box */
.drawer-recap-box {
  background-color: var(--bg-surface);
  border: 1.5px dashed var(--red-border);
  border-radius: var(--radius-md);
  padding: 0.85rem;
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
}

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

.recap-title {
  font-size: 0.85rem;
  color: var(--red-main);
}

.recap-badge-small {
  font-size: 0.72rem;
  font-weight: 800;
  padding: 0.15rem 0.45rem;
  border-radius: var(--radius-full);
  background-color: var(--red-bg);
  color: var(--red-text);
}

.recap-subtext {
  font-size: 0.75rem;
  color: var(--text-dim);
  line-height: 1.35;
}

.recap-box-actions {
  display: flex;
  gap: 0.45rem;
  margin-top: 0.25rem;
}

.btn-recap-primary {
  flex: 1;
  padding: 0.45rem 0.75rem;
  background-color: var(--red-main);
  color: #fff;
  font-size: 0.78rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition-fast);
}

.btn-recap-primary:hover {
  background-color: #b91c1c;
}

.btn-recap-clear {
  padding: 0.45rem 0.65rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-dim);
  font-size: 0.78rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition-fast);
}

.btn-recap-clear:hover {
  color: var(--red-main);
  border-color: var(--red-border);
}

.tool-btn {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.7rem;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-dim);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background-color: var(--bg-surface);
  transition: var(--transition-fast);
}

.tool-btn:hover {
  color: var(--amber-main);
  border-color: var(--amber-border);
}

.tool-btn.active {
  background-color: var(--amber-bg);
  color: var(--amber-text);
  border-color: var(--amber-border);
}

/* Sentence Area */
.sentence-box {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem 1.75rem;
}

.sentence-text {
  font-size: 1.15rem;
  line-height: 1.75;
  color: var(--text-main);
  font-weight: 500;
}

.sentence-text .blank {
  display: inline-block;
  padding: 0 0.5rem;
  margin: 0 0.15rem;
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--primary);
  border-bottom: 2.5px solid var(--primary);
  background-color: rgba(99, 102, 241, 0.08);
  border-radius: 4px;
}

/* Options */
.options-container {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.option-btn {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1rem 1.25rem;
  background-color: var(--bg-card);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  text-align: left;
  transition: var(--transition-fast);
  cursor: pointer;
}

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

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

.option-letter {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  min-width: 32px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-surface);
  font-weight: 800;
  font-size: 0.85rem;
  border: 1px solid var(--border-color);
  color: var(--text-muted);
}

.option-btn.selected .option-letter {
  background-color: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

.option-text {
  font-size: 1rem;
  font-weight: 600;
  flex: 1;
  line-height: 1.4;
}

.option-key-hint {
  font-size: 0.7rem;
  font-family: var(--font-mono);
  padding: 0.2rem 0.4rem;
  border-radius: 4px;
  background-color: var(--bg-surface);
  color: var(--text-dim);
  border: 1px solid var(--border-color);
}

/* Answer Feedback States */
.option-btn.correct {
  border-color: var(--green-main) !important;
  background-color: var(--green-bg) !important;
  color: var(--green-text) !important;
}

.option-btn.correct .option-letter {
  background-color: var(--green-main) !important;
  color: #fff !important;
  border-color: var(--green-main) !important;
}

.option-btn.wrong {
  border-color: var(--red-main) !important;
  background-color: var(--red-bg) !important;
  color: var(--red-text) !important;
}

.option-btn.wrong .option-letter {
  background-color: var(--red-main) !important;
  color: #fff !important;
  border-color: var(--red-main) !important;
}

/* ==========================================================================
   Feedback & AI Actions Panel
   ========================================================================== */

.feedback-panel {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  border-top: 1px solid var(--border-color);
  padding-top: 1.25rem;
  animation: fadeIn 0.2s ease;
}

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

.feedback-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.85rem 1.25rem;
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  font-weight: 700;
}

.feedback-banner.correct {
  background-color: var(--green-bg);
  color: var(--green-text);
  border: 1px solid var(--green-border);
}

.feedback-banner.wrong {
  background-color: var(--red-bg);
  color: var(--red-text);
  border: 1px solid var(--red-border);
}

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

.feedback-key-info strong {
  font-family: var(--font-mono);
  font-size: 1.1rem;
}

/* Explanation Actions */
.explanation-actions {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 0.65rem;
}

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

.ai-btn-primary {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, #1a73e8, #4285f4);
  color: #fff;
  font-weight: 700;
  font-size: 0.88rem;
  box-shadow: 0 2px 6px rgba(26, 115, 232, 0.25);
  transition: var(--transition-fast);
}

.ai-btn-primary:hover {
  background: linear-gradient(135deg, #1557b0, #1a73e8);
  transform: translateY(-1px);
}

.ai-btn-secondary, .ai-btn-tertiary {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  padding: 0.75rem 0.85rem;
  border-radius: var(--radius-md);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--text-main);
  transition: var(--transition-fast);
}

.ai-btn-secondary:hover, .ai-btn-tertiary:hover {
  background-color: var(--bg-surface-hover);
}

/* Details Accordion */
.prompt-details {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  font-size: 0.8rem;
}

.prompt-details summary {
  padding: 0.6rem 0.85rem;
  cursor: pointer;
  background-color: var(--bg-surface);
  font-weight: 600;
  color: var(--text-muted);
}

.prompt-code {
  padding: 0.85rem;
  background-color: var(--bg-app);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  white-space: pre-wrap;
  color: var(--text-dim);
  max-height: 200px;
  overflow-y: auto;
}

/* Scan Preview */
.scan-preview-box {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.85rem;
}

.scan-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.subtle-link {
  color: var(--primary);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.8rem;
}
.subtle-link:hover { text-decoration: underline; }

.scan-image-wrap {
  max-height: 480px;
  overflow-y: auto;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  background-color: #fff;
  display: flex;
  justify-content: center;
}

.scan-image-wrap img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* ==========================================================================
   Card Footer Navigation
   ========================================================================== */

.card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  border-top: 1px solid var(--border-color);
  padding-top: 1.25rem;
}

.nav-btn {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.65rem 1.15rem;
  border-radius: var(--radius-md);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  font-weight: 700;
  font-size: 0.88rem;
  color: var(--text-main);
  transition: var(--transition-fast);
}

.nav-btn:hover:not(:disabled) {
  background-color: var(--bg-surface-hover);
  border-color: var(--primary);
}

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

.action-btn.check-btn {
  padding: 0.75rem 2rem;
  border-radius: var(--radius-md);
  background-color: var(--primary);
  color: #fff;
  font-weight: 800;
  font-size: 0.95rem;
  box-shadow: 0 4px 10px rgba(67, 56, 202, 0.25);
  transition: var(--transition-fast);
}

.action-btn.check-btn:hover:not(:disabled) {
  background-color: var(--primary-hover);
  transform: translateY(-1px);
}

.action-btn.check-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.keyboard-hints {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  margin-top: 0.75rem;
  font-size: 0.75rem;
  color: var(--text-dim);
}

.key-tag {
  display: inline-block;
  padding: 0.15rem 0.35rem;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.7rem;
  border-radius: 4px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-main);
}

/* ==========================================================================
   Sidebar Drawer (Question Navigator)
   ========================================================================== */

.sidebar-drawer {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  position: sticky;
  top: 80px;
}

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

.drawer-header h2 {
  font-size: 1.05rem;
  font-weight: 800;
}

.close-btn {
  font-size: 1.5rem;
  line-height: 1;
  color: var(--text-dim);
  padding: 0.25rem;
}

/* Filter Tabs */
.filter-tabs {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.35rem;
  background-color: var(--bg-surface);
  padding: 4px;
  border-radius: var(--radius-sm);
}

.filter-tab {
  padding: 0.35rem 0.5rem;
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--text-dim);
  border-radius: 4px;
  text-align: center;
  transition: var(--transition-fast);
}

.filter-tab.active {
  background-color: var(--bg-card);
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

/* Question Grid */
.grid-section-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.65rem;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text-dim);
}

.question-grid {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 0.45rem;
}

.q-chip {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-color);
  font-weight: 700;
  font-size: 0.8rem;
  color: var(--text-muted);
  cursor: pointer;
  position: relative;
  transition: var(--transition-fast);
}

.q-chip:hover {
  border-color: var(--primary);
  background-color: var(--bg-surface-hover);
}

.q-chip.active {
  outline: 2.5px solid var(--primary);
  outline-offset: 1px;
}

.q-chip.correct {
  background-color: var(--green-main);
  color: #fff;
  border-color: var(--green-main);
}

.q-chip.wrong {
  background-color: var(--red-main);
  color: #fff;
  border-color: var(--red-main);
}

.q-chip.flagged::after {
  content: '';
  position: absolute;
  top: 2px;
  right: 2px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--amber-main);
}

/* Drawer Summary Card */
.drawer-summary-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
}

.drawer-summary-card h3 {
  font-size: 0.85rem;
  font-weight: 800;
  margin-bottom: 0.65rem;
}

.summary-row {
  display: flex;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.35rem;
}

.summary-row span:last-child {
  font-weight: 700;
  color: var(--text-main);
  font-family: var(--font-mono);
}

.text-green { color: var(--green-main) !important; }

.summary-progress-bar {
  width: 100%;
  height: 6px;
  background-color: var(--border-color);
  border-radius: var(--radius-full);
  margin-top: 0.65rem;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--green-main));
  transition: width 0.3s ease;
}

/* Resource Links */
.drawer-resources {
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
}

.drawer-resources h4 {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-dim);
  margin-bottom: 0.5rem;
}

.resource-link {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--primary);
  text-decoration: none;
  padding: 0.35rem 0;
}
.resource-link:hover { text-decoration: underline; }

/* ==========================================================================
   Search Modal
   ========================================================================== */

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.55);
  backdrop-filter: blur(4px);
  z-index: 100;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 4rem 1rem 1rem;
}

.modal-card {
  width: 100%;
  max-width: 620px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
  font-size: 1rem;
  font-weight: 800;
}

.modal-search-input {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.75rem 1.25rem;
  border-bottom: 1px solid var(--border-color);
  background-color: var(--bg-surface);
}

.modal-search-input input {
  width: 100%;
  border: none;
  background: transparent;
  font-size: 0.95rem;
  color: var(--text-main);
  outline: none;
}

.search-results-list {
  max-height: 380px;
  overflow-y: auto;
  padding: 0.5rem;
}

.search-result-item {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition-fast);
}

.search-result-item:hover {
  background-color: var(--bg-surface);
}

.search-item-meta {
  display: flex;
  gap: 0.45rem;
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 0.25rem;
}

.search-item-sentence {
  font-size: 0.85rem;
  color: var(--text-main);
  line-height: 1.4;
  overflow: hidden;
  text-overflow: ellipsis;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

/* ==========================================================================
   Toast
   ========================================================================== */

.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background-color: var(--text-main);
  color: var(--bg-card);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-full);
  font-weight: 700;
  font-size: 0.85rem;
  box-shadow: var(--shadow-lg);
  z-index: 120;
  opacity: 0;
  pointer-events: none;
  transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.3s ease;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ==========================================================================
   Responsive Breakpoints
   ========================================================================== */

.mobile-only { display: none !important; }

@media (max-width: 1024px) {
  .app-container {
    grid-template-columns: 1fr;
  }

  .desktop-only { display: none !important; }
  .mobile-only { display: flex !important; }

  /* Mobile Drawer */
  .sidebar-drawer {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: 320px;
    z-index: 90;
    border-radius: 0;
    transform: translateX(100%);
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    overflow-y: auto;
  }

  .sidebar-drawer.open {
    transform: translateX(0);
  }
}

@media (max-width: 640px) {
  .header-inner {
    padding: 0.65rem 0.85rem;
  }

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

  .question-card {
    padding: 1.15rem;
  }

  .sentence-box {
    padding: 1rem;
  }

  .sentence-text {
    font-size: 1rem;
  }

  .option-btn {
    padding: 0.85rem 1rem;
  }

  .action-btn.check-btn {
    padding: 0.65rem 1.25rem;
    font-size: 0.88rem;
  }
}