/* ============================================================================
   TBank Design System - macOS-Native Theme
   Based on comprehensive visual audit & accessibility improvements
   ============================================================================ */

/* ============================================================================
   1. DESIGN TOKENS - System-First Approach
   ============================================================================ */

:root {
  /* Tell browser to optimize form controls for light/dark */
  color-scheme: light dark;

  /* ===== Typography ===== */
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Oxygen", "Ubuntu", sans-serif;
  --font-vignette: Georgia, "Times New Roman", serif;
  --font-mono: "SF Mono", Consolas, Monaco, monospace;

  /* Base size optimized for macOS comfort */
  --fs-body: 17px;
  --lh: 1.55;
  --lh-tight: 1.25;
  --lh-relaxed: 1.75;
  --lh-vignette: 1.8;

  /* Modular scale (1.125 - Major Second) */
  --scale-sm: 0.889;
  --scale-base: 1;
  --scale-1: 1.125;
  --scale-2: 1.266;
  --scale-3: 1.424;
  --scale-4: 1.602;

  /* ===== Semantic Colors (Canvas-based, system adaptive) ===== */
  --bg: Canvas;
  --surface: color-mix(in oklab, Canvas 94%, CanvasText 6%);
  --surface-2: color-mix(in oklab, Canvas 90%, CanvasText 10%);
  --fg: CanvasText;
  --fg-muted: color-mix(in oklab, CanvasText 70%, Canvas 30%);
  --border: color-mix(in oklab, CanvasText 12%, Canvas 88%);
  --border-strong: color-mix(in oklab, CanvasText 20%, Canvas 80%);

  /* System accent color (respects macOS preference) */
  --accent: AccentColor;
  --accent-contrast: AccentColorText;
  --focus: AccentColor;

  /* State colors (WCAG-compliant, color-blind safe) */
  --success: #16a34a;
  --success-bg: #f0fdf4;
  --success-fg: #15803d;
  --danger: #dc2626;
  --danger-bg: #fef2f2;
  --danger-fg: #b91c1c;
  --warning: #d97706;
  --warning-bg: #fef3c7;
  --warning-fg: #92400e;
  --info: #3182ce;
  --info-bg: #eff6ff;
  --info-fg: #1e40af;

  /* ===== Spacing (4/8 Grid System) ===== */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;

  /* ===== Border Radius ===== */
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 999px;

  /* ===== Shadows ===== */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 4px 8px rgba(0, 0, 0, 0.12);
  --shadow-xl: 0 8px 16px rgba(0, 0, 0, 0.15);

  /* Focus ring */
  --ring: 2px;
  --ring-offset: 2px;

  /* ===== Timing & Easing ===== */
  --t-instant: 0ms;
  --t-quick: 120ms;
  --t-normal: 200ms;
  --t-slow: 300ms;
  --ease: cubic-bezier(0.2, 0.8, 0.2, 1);
  --ease-in: cubic-bezier(0.4, 0, 1, 1);
  --ease-out: cubic-bezier(0, 0, 0.2, 1);
}

/* ===== Dark Mode Overrides ===== */
@media (prefers-color-scheme: dark) {
  :root:not(.force-light) {
    --bg: #0f1419;
    --surface: #1f2937;
    --surface-2: #374151;
    --fg: #e5e7eb;
    --fg-muted: #9ca3af;
    --border: #374151;
    --border-strong: #4b5563;

    /* Adjust state colors for dark mode */
    --success-bg: #064e3b;
    --success-fg: #a7f3d0;
    --danger-bg: #7f1d1d;
    --danger-fg: #fca5a5;
    --warning-bg: #78350f;
    --warning-fg: #fde68a;
    --info-bg: #1e3a5f;
    --info-fg: #bae6fd;

    /* Increase line-height slightly in dark mode for better readability */
    --lh: 1.6;

    /* Softer shadows for dark mode */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 4px 8px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 8px 16px rgba(0, 0, 0, 0.6);
  }
}

/* Manual dark mode override class (for user toggle) */
html.dark-mode,
body.dark-mode {
  --bg: #0f1419;
  --surface: #1f2937;
  --surface-2: #374151;
  --fg: #e5e7eb;
  --fg-muted: #9ca3af;
  --border: #374151;
  --border-strong: #4b5563;
  --success-bg: #064e3b;
  --success-fg: #a7f3d0;
  --danger-bg: #7f1d1d;
  --danger-fg: #fca5a5;
  --warning-bg: #78350f;
  --warning-fg: #fde68a;
  --info-bg: #1e3a5f;
  --info-fg: #bae6fd;
  --lh: 1.6;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 4px 8px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 8px 16px rgba(0, 0, 0, 0.6);
}

/* ============================================================================
   2. BASE STYLES
   ============================================================================ */

body {
  font: 400 var(--fs-body) / var(--lh) var(--font-sans);
  background: var(--bg);
  color: var(--fg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography scale application */
h1 {
  font-size: calc(1rem * var(--scale-3));
  line-height: var(--lh-tight);
  text-wrap: balance;
  font-weight: 700;
}

h2 {
  font-size: calc(1rem * var(--scale-2));
  line-height: var(--lh-tight);
  text-wrap: balance;
  font-weight: 600;
}

h3 {
  font-size: calc(1rem * var(--scale-1));
  line-height: var(--lh-tight);
  font-weight: 600;
}

/* Tabular numbers for stats and counters */
.session-stats,
.timer-display,
#question-counter,
#answered-count,
#correct-count,
#percentage,
.progress-info,
.question-menu-stats {
  font-variant-numeric: tabular-nums;
}

/* Main content constraint */
main {
  max-width: 72ch;
  margin-inline: auto;
  padding: var(--space-6) var(--space-4);
}

/* ============================================================================
   3. UNIVERSAL FOCUS RING (Keyboard Accessibility)
   ============================================================================ */

/* Remove default outlines first */
:where(button, [role="button"], a, input, select, textarea, [tabindex]:not([tabindex="-1"])) {
  outline: none;
}

/* Apply visible focus ring on keyboard navigation */
:where(button, [role="button"], a, input, select, textarea, [tabindex]:not([tabindex="-1"])):focus-visible {
  box-shadow:
    0 0 0 var(--ring-offset) color-mix(in oklab, var(--bg) 85%, var(--focus) 15%),
    0 0 0 calc(var(--ring) + var(--ring-offset)) var(--focus);
  outline: none;
  z-index: 1;
  position: relative;
}

/* Special focus for radio inputs within answer choices */
.answer-choice:focus-within {
  box-shadow:
    0 0 0 var(--ring-offset) color-mix(in oklab, var(--bg) 85%, var(--focus) 15%),
    0 0 0 calc(var(--ring) + var(--ring-offset)) var(--focus);
}

/* ============================================================================
   4. BUTTON COMPONENT STATES
   ============================================================================ */

button,
.btn {
  min-height: 44px;
  min-width: 44px;
  padding: 0 var(--space-4);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--fg);
  font: inherit;
  font-weight: 600;
  cursor: pointer;
  transition:
    background var(--t-quick) var(--ease),
    border-color var(--t-quick) var(--ease),
    transform var(--t-quick) var(--ease),
    box-shadow var(--t-quick) var(--ease);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
}

/* Hover state */
button:hover:not(:disabled),
.btn:hover:not(:disabled) {
  background: color-mix(in oklab, var(--surface) 90%, var(--fg) 10%);
  border-color: var(--border-strong);
}

/* Active/pressed state */
button:active:not(:disabled),
.btn:active:not(:disabled) {
  transform: translateY(1px);
}

/* Disabled state */
button:disabled,
.btn:disabled,
button[aria-disabled="true"],
.btn[aria-disabled="true"] {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

/* Primary button variant */
button.primary,
.button-primary,
.submit-btn {
  background: var(--accent);
  color: var(--accent-contrast);
  border-color: var(--accent);
}

button.primary:hover:not(:disabled),
.button-primary:hover:not(:disabled),
.submit-btn:hover:not(:disabled) {
  filter: brightness(1.1);
}

/* Secondary button variant */
button.secondary,
.button-secondary {
  background: transparent;
  border-color: var(--border-strong);
  color: var(--fg);
}

button.secondary:hover:not(:disabled),
.button-secondary:hover:not(:disabled) {
  background: var(--surface);
}

/* Danger button variant */
button.danger,
.menu-action-btn:contains("Reset") {
  background: var(--danger-bg);
  color: var(--danger);
  border-color: var(--danger);
}

button.danger:hover:not(:disabled) {
  background: var(--danger);
  color: white;
}

/* ============================================================================
   5. MCQ SEMANTIC MARKUP (Fieldset + Legend + Labels)
   ============================================================================ */

/* Fieldset reset */
.mcq,
.answer-choices {
  border: none;
  padding: 0;
  margin: 0;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

/* Legend styling */
.mcq legend,
.answer-choices legend {
  font-weight: 600;
  font-size: calc(1rem * var(--scale-1));
  padding: 0;
  margin-bottom: var(--space-4);
  color: var(--fg);
}

/* MCQ option as label wrapper */
.mcq-option,
.answer-choice {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--surface);
  cursor: pointer;
  transition: all var(--t-quick) var(--ease);
  min-height: 44px;
}

.mcq-option:hover,
.answer-choice:hover {
  background: color-mix(in oklab, var(--surface) 94%, var(--fg) 6%);
  border-color: var(--border-strong);
}

/* Selected state */
.mcq-option:has(input:checked),
.answer-choice:has(input:checked),
.answer-choice.answer-selected {
  background: color-mix(in oklab, var(--accent) 10%, var(--surface) 90%);
  border-color: var(--accent);
}

.mcq-option:has(input:checked) .mcq-text,
.answer-choice:has(input:checked) .choice-text {
  font-weight: 600;
}

/* Radio input (visually hidden but accessible) */
.mcq-option input[type="radio"],
.answer-choice input[type="radio"] {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

/* Choice letter/marker */
.choice-letter {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--surface-2);
  border: 2px solid var(--border-strong);
  font-weight: 700;
  font-size: calc(1rem * var(--scale-1));
  transition: all var(--t-quick) var(--ease);
}

.mcq-option:has(input:checked) .choice-letter,
.answer-choice:has(input:checked) .choice-letter,
.answer-choice.answer-selected .choice-letter {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-contrast);
}

/* Correct/Incorrect states with icons */
.answer-choice.answer-correct {
  background: var(--success-bg);
  border-color: var(--success);
}

.answer-choice.answer-correct .choice-letter {
  background: var(--success);
  border-color: var(--success);
  color: white;
}

.answer-choice.answer-correct::after {
  content: "✓ Correct";
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--success);
  margin-left: auto;
}

.answer-choice.answer-incorrect {
  background: var(--danger-bg);
  border-color: var(--danger);
}

.answer-choice.answer-incorrect .choice-letter {
  background: var(--danger);
  border-color: var(--danger);
  color: white;
}

.answer-choice.answer-incorrect::after {
  content: "✗ Incorrect";
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--danger);
  margin-left: auto;
}

/* Strike-through toggle button within option */
.strike,
.eliminate-btn {
  min-height: 32px;
  min-width: 32px;
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: transparent;
  color: var(--fg-muted);
  font-size: var(--text-xs);
  cursor: pointer;
  opacity: 0;
  transition: all var(--t-quick) var(--ease);
}

.mcq-option:hover .strike,
.answer-choice:hover .eliminate-btn {
  opacity: 1;
}

.strike[aria-pressed="true"],
.answer-choice.eliminated .eliminate-btn {
  opacity: 1;
  background: var(--danger-bg);
  border-color: var(--danger);
  color: var(--danger);
}

/* Strike-through effect */
.strike[aria-pressed="true"] ~ .mcq-text,
.answer-choice.eliminated .choice-text {
  text-decoration: line-through;
  text-decoration-color: var(--danger);
  text-decoration-thickness: 2px;
  opacity: 0.6;
}

.answer-choice.eliminated {
  opacity: 0.5;
}

/* ============================================================================
   6. MODAL DIALOGS (Focus Trap & Accessibility)
   ============================================================================ */

.modal {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.75);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: var(--space-4);
  backdrop-filter: blur(4px);
}

.modal[hidden] {
  display: none !important;
}

.modal-content {
  background: var(--surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  max-width: 600px;
  width: 100%;
  max-height: 90vh;
  overflow: auto;
  display: flex;
  flex-direction: column;
}

.modal-header {
  padding: var(--space-6) var(--space-6) var(--space-4);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-header h2 {
  margin: 0;
  color: var(--fg);
}

.modal-body {
  padding: var(--space-6);
  color: var(--fg);
  flex: 1;
  overflow: auto;
}

.modal-footer {
  padding: var(--space-4) var(--space-6) var(--space-6);
  border-top: 1px solid var(--border);
  display: flex;
  gap: var(--space-3);
  justify-content: flex-end;
}

/* Close button */
.close-btn {
  min-width: 44px;
  min-height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  background: transparent;
  color: var(--fg-muted);
  font-size: 2rem;
  line-height: 1;
  cursor: pointer;
  border-radius: var(--radius-sm);
  transition: all var(--t-quick) var(--ease);
}

.close-btn:hover {
  background: var(--surface-2);
  color: var(--fg);
}

/* ============================================================================
   7. LIVE REGIONS & PROGRESS AFFORDANCES
   ============================================================================ */

/* Screen reader announcements */
#sr-announcements,
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Progress info with live region */
.progress-info {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.session-stats {
  display: flex;
  gap: var(--space-4);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--fg-muted);
}

/* Timer display */
.timer-display {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-weight: 600;
  color: var(--fg);
}

/* Timer warning states */
.timer-display.timer-caution {
  background: var(--warning-bg);
  border-color: var(--warning);
  color: var(--warning-fg);
}

.timer-display.timer-warning {
  background: var(--danger-bg);
  border-color: var(--danger);
  color: var(--danger-fg);
  animation: timer-pulse 1s ease-in-out infinite;
}

@keyframes timer-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.8; }
}

/* ============================================================================
   8. SPACING & RHYTHM UTILITIES
   ============================================================================ */

/* Vertical rhythm helpers */
.stack-2 > * + * { margin-top: var(--space-2); }
.stack-3 > * + * { margin-top: var(--space-3); }
.stack-4 > * + * { margin-top: var(--space-4); }
.stack-6 > * + * { margin-top: var(--space-6); }

/* Consistent card/surface spacing */
.card,
.question-display,
.question-content {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-md);
}

/* Question vignette */
.vignette {
  background: color-mix(in oklab, var(--surface) 50%, var(--bg) 50%);
  border-left: 4px solid var(--accent);
  padding: var(--space-5);
  border-radius: var(--radius-sm);
  font-family: var(--font-vignette);
  font-size: calc(1rem * var(--scale-1));
  line-height: var(--lh-vignette);
  max-width: 70ch;
}

/* Question text emphasis */
.question-text {
  font-weight: 600;
  font-size: calc(1rem * var(--scale-1));
  line-height: var(--lh-relaxed);
  padding: var(--space-3) 0;
  border-top: 2px solid var(--border);
  border-bottom: 2px solid var(--border);
  margin: var(--space-4) 0;
}

/* ============================================================================
   9. TAP TARGET NORMALIZATION (≥44×44px)
   ============================================================================ */

/* All interactive elements */
button,
[role="button"],
a[href],
input[type="checkbox"],
input[type="radio"],
select,
.grid-question-btn,
.menu-btn,
.settings-btn,
.nav-btn,
.filter-btn {
  min-width: 44px;
  min-height: 44px;
}

/* Question grid buttons */
.grid-question-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 48px;
  min-height: 48px;
  padding: var(--space-2);
  border-radius: var(--radius-sm);
  border: 2px solid var(--border);
  background: var(--surface);
  font-weight: 700;
  cursor: pointer;
  transition: all var(--t-quick) var(--ease);
}

.grid-question-btn:hover {
  background: var(--surface-2);
  border-color: var(--border-strong);
}

.grid-question-btn.current {
  border-color: var(--accent);
  background: color-mix(in oklab, var(--accent) 20%, var(--surface) 80%);
}

.grid-question-btn.correct {
  background: var(--success);
  border-color: var(--success);
  color: white;
}

.grid-question-btn.incorrect {
  background: var(--danger);
  border-color: var(--danger);
  color: white;
}

/* ============================================================================
   10. PERFORMANCE & MOTION
   ============================================================================ */

/* Honor reduced motion preference */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* Skip to content link */
.skip-to-content {
  position: absolute;
  top: -100px;
  left: var(--space-4);
  background: var(--accent);
  color: var(--accent-contrast);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  font-weight: 600;
  z-index: 9999;
  transition: top var(--t-quick) var(--ease);
}

.skip-to-content:focus {
  top: var(--space-4);
}

/* ============================================================================
   11. RESPONSIVE & SAFE AREAS
   ============================================================================ */

/* iOS safe area support */
.quiz-header {
  padding-top: max(var(--space-4), env(safe-area-inset-top));
}

.quiz-container {
  padding-bottom: max(var(--space-6), env(safe-area-inset-bottom));
}

.question-menu {
  padding-top: max(var(--space-4), env(safe-area-inset-top));
  padding-bottom: max(var(--space-4), env(safe-area-inset-bottom));
  padding-right: max(var(--space-4), env(safe-area-inset-right));
}

/* Container queries for responsive components */
@container (max-width: 600px) {
  .modal-content {
    border-radius: 0;
    max-height: 100vh;
  }
}

/* Mobile breakpoint */
@media (max-width: 640px) {
  :root {
    --fs-body: 16px;
  }

  .modal-content {
    max-width: 100%;
  }

  .question-grid {
    grid-template-columns: repeat(auto-fill, minmax(48px, 1fr));
  }
}

/* ============================================================================
   12. UTILITY CLASSES
   ============================================================================ */

/* Text utilities */
.text-muted { color: var(--fg-muted); }
.text-success { color: var(--success); }
.text-danger { color: var(--danger); }
.text-warning { color: var(--warning); }

/* Background utilities */
.bg-surface { background: var(--surface); }
.bg-success { background: var(--success-bg); }
.bg-danger { background: var(--danger-bg); }
.bg-warning { background: var(--warning-bg); }

/* Border utilities */
.border { border: 1px solid var(--border); }
.border-strong { border-color: var(--border-strong); }
.rounded { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }

/* Spacing utilities */
.p-4 { padding: var(--space-4); }
.p-6 { padding: var(--space-6); }
.m-0 { margin: 0; }
.mt-4 { margin-top: var(--space-4); }
.mb-4 { margin-bottom: var(--space-4); }
.gap-4 { gap: var(--space-4); }

/* Flexbox utilities */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }

/* Grid utilities */
.grid { display: grid; }
.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }

/* ============================================================================
   End of TBank Design System Theme
   ============================================================================ */