/* ===== DESIGN TOKENS ===== */
:root {
  --color-primary: #2e8fb5;
  --color-primary-dark: #2578a0;
  --color-primary-light: #3aabd1;
  --color-primary-bg: #e6f4fa;
  --color-primary-hover: #f0f8fb;

  --color-success: #27ae60;
  --color-success-bg: #f0faf4;
  --color-success-light: #e0f5ea;
  --color-success-hover: #219a52;

  --color-error: #e74c3c;
  --color-error-bg: #fde8e8;
  --color-error-dark: #c0392b;

  --color-warning-border: #ffb300;
  --color-warning-bg: #fff8e1;
  --color-warning-text: #e65100;

  --color-bg: #eef1f5;
  --color-surface: #fff;
  --color-surface-raised: #f8f9fa;
  --color-surface-subtle: #f0f2f5;
  --color-image-frame: #f8f9fb;
  --color-border: #e0e0e0;
  --color-divider: #eee;
  --color-muted: #888;
  --color-text-secondary: #666;
  --color-text: #1a1a2e;
  --color-overlay: rgba(26, 26, 46, 0.5);
  --color-skeleton-a: #e8ebef;
  --color-skeleton-b: #f4f6f8;
  --color-on-primary: #fff;
  --color-modal-secondary-text: #444;
  --color-modal-secondary-hover: #ccc;
  --color-focus-ring: rgba(46, 143, 181, 0.15);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-pill: 20px;

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.07);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.1);

  --font-family: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.85rem;
  --font-size-base: 0.95rem;
  --font-size-md: 1.05rem;
  --font-size-lg: 1.1rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 1.6rem;
  --font-size-3xl: 2.8rem;

  --container-max: 860px;
  --transition: 0.2s ease;
}

[data-theme="dark"] {
  color-scheme: dark;

  --color-primary: #4eb3d8;
  --color-primary-dark: #3a9fc4;
  --color-primary-light: #6ec4e6;
  --color-primary-bg: #1a3540;
  --color-primary-hover: #1e3d4a;

  --color-success: #3ecf7a;
  --color-success-bg: #1a3328;
  --color-success-light: #1f4032;
  --color-success-hover: #35b86a;

  --color-error: #f07167;
  --color-error-bg: #3a2220;
  --color-error-dark: #e85549;

  --color-warning-border: #ffb300;
  --color-warning-bg: #3a3018;
  --color-warning-text: #ffb74d;

  --color-bg: #12151a;
  --color-surface: #1c2128;
  --color-surface-raised: #252b33;
  --color-surface-subtle: #2a313a;
  --color-image-frame: #252b33;
  --color-border: #343b44;
  --color-divider: #343b44;
  --color-muted: #8b949e;
  --color-text-secondary: #adbac7;
  --color-text: #e6edf3;
  --color-overlay: rgba(0, 0, 0, 0.65);
  --color-skeleton-a: #2a313a;
  --color-skeleton-b: #343b44;
  --color-modal-secondary-text: #c9d1d9;
  --color-modal-secondary-hover: #444c56;
  --color-focus-ring: rgba(78, 179, 216, 0.2);

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.45);
}

[data-theme="dark"] body {
  background-image:
    radial-gradient(ellipse at 20% 0%, rgba(46, 143, 181, 0.08) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 100%, rgba(46, 143, 181, 0.05) 0%, transparent 50%);
}

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

body {
  font-family: var(--font-family);
  background: var(--color-bg);
  background-image:
    radial-gradient(ellipse at 20% 0%, rgba(58, 171, 209, 0.12) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 100%, rgba(46, 143, 181, 0.08) 0%, transparent 50%);
  color: var(--color-text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-size: var(--font-size-base);
  line-height: 1.5;
}

.container {
  flex: 1;
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 16px;
}

/* ===== HERO BANNER ===== */
.hero {
  background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-primary) 50%, var(--color-primary-dark) 100%);
  color: var(--color-on-primary);
  text-align: center;
  padding: 20px 20px 24px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" width="60" height="60"><path d="M0 30 L30 0 L60 30 L30 60Z" fill="rgba(255,255,255,0.04)"/></svg>') repeat;
  pointer-events: none;
}

.hero-inner {
  position: relative;
  max-width: var(--container-max);
  margin: 0 auto;
}

.hero-title-link {
  color: inherit;
  text-decoration: none;
  display: inline-block;
}

.hero-title-link:hover .hero-title {
  opacity: 0.92;
}

.hero-title {
  font-size: var(--font-size-2xl);
  font-weight: 800;
  letter-spacing: 0.3px;
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  line-height: 1.2;
}

.hero-subtitle {
  font-size: var(--font-size-sm);
  font-weight: 500;
  opacity: 0.9;
  margin-top: 6px;
  letter-spacing: 0.2px;
}

/* ===== SITE NAV ===== */
.site-nav {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 20;
  padding: 10px 16px;
}

.site-nav-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 12px;
}

.site-nav-links {
  flex: 1;
  display: flex;
  justify-content: center;
  gap: 6px;
}

.site-nav-link {
  padding: 8px 16px;
  border-radius: var(--radius-pill);
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: background var(--transition), color var(--transition);
}

.site-nav-link:hover {
  color: var(--color-primary);
  background: var(--color-primary-bg);
}

.site-nav-link.active {
  color: var(--color-primary);
  background: var(--color-primary-bg);
}

.theme-toggle {
  width: 36px;
  height: 36px;
  margin-left: auto;
  flex-shrink: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface-subtle);
  color: var(--color-text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--transition), color var(--transition), border-color var(--transition);
  font-family: inherit;
  flex-shrink: 0;
}

.theme-toggle:hover {
  background: var(--color-primary-bg);
  color: var(--color-primary);
  border-color: var(--color-primary);
}

.theme-toggle svg {
  width: 18px;
  height: 18px;
}

.theme-icon-light {
  display: none;
}

.theme-icon-dark {
  display: flex;
}

[data-theme="dark"] .theme-icon-dark {
  display: none;
}

[data-theme="dark"] .theme-icon-light {
  display: block;
}

/* ===== HOME SCREEN ===== */
#home {
  text-align: center;
}

/* Resume banner */
.resume-banner {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  margin-bottom: 16px;
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  text-align: left;
}

.resume-icon {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: var(--color-warning-bg);
  color: var(--color-warning-text);
  display: flex;
  align-items: center;
  justify-content: center;
}

.resume-icon svg {
  width: 18px;
  height: 18px;
}

.resume-body {
  flex: 1;
  min-width: 0;
}

.resume-title {
  font-weight: 700;
  font-size: var(--font-size-sm);
  color: var(--color-text);
  line-height: 1.3;
  margin-bottom: 2px;
}

.resume-meta {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
}

.resume-actions {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 8px;
}

.resume-btn {
  padding: 7px 14px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.78rem;
  font-weight: 700;
  cursor: pointer;
  transition: background var(--transition), color var(--transition), border-color var(--transition);
  background: var(--color-primary);
  color: var(--color-on-primary);
  font-family: inherit;
  white-space: nowrap;
}

.resume-btn:hover {
  background: var(--color-primary-dark);
}

.resume-btn.discard {
  background: var(--color-surface);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}

.resume-btn.discard:hover {
  border-color: var(--color-muted);
  color: var(--color-text);
}

/* ===== HISTORY ACCORDION ===== */
.history-section {
  background: var(--color-surface);
  border-radius: var(--radius-md);
  margin-bottom: 16px;
  box-shadow: var(--shadow-sm);
  text-align: left;
  overflow: hidden;
}

.history-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 20px;
  cursor: pointer;
  user-select: none;
  transition: background var(--transition);
}

.history-header:hover {
  background: var(--color-surface-raised);
}

.history-header h3 {
  margin: 0;
  font-size: var(--font-size-base);
  font-weight: 700;
  color: var(--color-primary);
}

.history-toggle-icon {
  display: flex;
  align-items: center;
  color: var(--color-primary);
  transition: transform 0.25s ease;
}

.history-toggle-icon svg {
  width: 18px;
  height: 18px;
}

.history-toggle-icon.open {
  transform: rotate(90deg);
}

.history-body {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 0.3s ease;
  border-top: 1px solid transparent;
}

.history-body.open {
  grid-template-rows: 1fr;
  border-top-color: var(--color-divider);
}

.history-body-inner {
  overflow: hidden;
  min-height: 0;
  padding: 0 20px;
  opacity: 0;
  transition: opacity 0.25s ease, padding 0.3s ease;
}

.history-body.open .history-body-inner {
  padding: 16px 20px 18px;
  opacity: 1;
}

@media (prefers-reduced-motion: reduce) {
  .history-body,
  .history-body-inner,
  .history-toggle-icon {
    transition: none;
  }

  .history-body:not(.open) .history-body-inner {
    opacity: 0;
  }

  .history-body.open .history-body-inner {
    opacity: 1;
  }
}

#historyList {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.history-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: var(--radius-md);
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.history-item:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

.history-item-icon {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: var(--color-primary-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
}

.history-item.pass .history-item-icon {
  background: var(--color-success-bg);
  color: var(--color-success);
}

.history-item.fail .history-item-icon {
  background: var(--color-error-bg);
  color: var(--color-error);
}

.history-item-icon svg {
  width: 18px;
  height: 18px;
}

.history-item-body {
  flex: 1;
  min-width: 0;
}

.history-item-top {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 3px;
  flex-wrap: wrap;
}

.history-item-label {
  font-weight: 600;
  font-size: var(--font-size-sm);
  line-height: 1.3;
  color: var(--color-text);
}

.history-status {
  flex-shrink: 0;
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.3px;
  padding: 2px 8px;
  border-radius: var(--radius-pill);
}

.history-status.pass {
  background: var(--color-success-bg);
  color: var(--color-success);
}

.history-status.fail {
  background: var(--color-error-bg);
  color: var(--color-error);
}

.history-item-meta {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
}

.history-score {
  flex-shrink: 0;
  font-weight: 800;
  font-size: 1.05rem;
  line-height: 1;
}

.history-score.pass { color: var(--color-success); }
.history-score.fail { color: var(--color-error); }

.history-item-aside {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 12px;
}

.history-retake-btn {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 16px;
  border: none;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-on-primary);
  font-size: 0.78rem;
  font-weight: 700;
  cursor: pointer;
  font-family: inherit;
  transition: background var(--transition);
  white-space: nowrap;
}

.history-retake-btn:hover {
  background: var(--color-primary-dark);
}

.history-retake-btn svg {
  width: 14px;
  height: 14px;
}

.clear-history-btn {
  display: block;
  margin: 10px auto 0;
  padding: 6px 12px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-muted);
  font-size: var(--font-size-xs);
  cursor: pointer;
  transition: color var(--transition);
  font-family: inherit;
}

.clear-history-btn:hover {
  color: var(--color-error);
}

/* ===== SETUP CARDS ===== */
.setup-grid {
  display: grid;
  gap: 16px;
  margin-bottom: 16px;
}

.setup-card {
  background: var(--color-surface);
  border-radius: var(--radius-md);
  padding: 22px 24px;
  box-shadow: var(--shadow-sm);
  text-align: left;
}

.setup-card-title {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 14px;
}

.class-buttons {
  display: flex;
  gap: 8px;
}

.class-btn {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 10px 8px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  cursor: pointer;
  transition: all var(--transition);
  text-align: center;
  font-family: inherit;
  color: var(--color-text);
  min-width: 0;
}

.class-btn-icon {
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: var(--color-primary-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
  transition: background var(--transition), color var(--transition);
}

.class-btn-icon svg {
  width: 26px;
  height: 26px;
}

.class-btn-label {
  font-size: 0.78rem;
  font-weight: 600;
  line-height: 1.25;
}

.class-btn:hover {
  border-color: var(--color-primary);
  background: var(--color-primary-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.class-btn.selected {
  border-color: var(--color-primary);
  background: var(--color-primary-bg);
  color: var(--color-primary-dark);
}

.class-btn.selected .class-btn-icon {
  background: var(--color-primary);
  color: var(--color-on-primary);
}

.class-btn.selected .class-btn-label {
  color: var(--color-primary-dark);
}

/* Unit picker (unified) */
.unit-picker-trigger {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
  padding: 14px 16px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  cursor: pointer;
  font-family: inherit;
  text-align: left;
  transition: border-color var(--transition), background var(--transition);
}

.unit-picker-trigger:hover,
.unit-picker-trigger:focus-visible {
  border-color: var(--color-primary);
  background: var(--color-primary-hover);
  outline: none;
}

.unit-picker-icon {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: var(--color-primary-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
}

.unit-picker-icon svg {
  width: 20px;
  height: 20px;
}

.unit-picker-icon.completed {
  background: var(--color-success-bg);
  color: var(--color-success);
}

.unit-picker-text {
  flex: 1;
  min-width: 0;
}

.unit-picker-label {
  display: block;
  font-weight: 700;
  font-size: var(--font-size-sm);
  color: var(--color-text);
  line-height: 1.3;
}

.unit-picker-meta {
  display: block;
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  margin-top: 2px;
}

.unit-picker-chevron {
  flex-shrink: 0;
  color: var(--color-primary);
  display: flex;
  align-items: center;
}

.unit-picker-chevron svg {
  width: 20px;
  height: 20px;
}

.unit-sheet-overlay {
  position: fixed;
  inset: 0;
  z-index: 900;
  background: var(--color-overlay);
  backdrop-filter: blur(4px);
  display: none;
  align-items: flex-end;
  justify-content: center;
  animation: fadeIn 0.2s ease;
}

.unit-sheet {
  width: 100%;
  max-height: 85vh;
  background: var(--color-surface);
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  display: flex;
  flex-direction: column;
  animation: sheetSlideUp 0.28s ease;
  box-shadow: var(--shadow-lg);
}

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

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

.unit-sheet-handle {
  width: 36px;
  height: 4px;
  background: var(--color-border);
  border-radius: 2px;
  margin: 10px auto 0;
  flex-shrink: 0;
}

.unit-sheet-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px 12px;
  border-bottom: 1px solid var(--color-divider);
  flex-shrink: 0;
}

.unit-sheet-header h3 {
  font-size: var(--font-size-lg);
  font-weight: 700;
  margin: 0;
}

.unit-sheet-close {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: none;
  border-radius: 50%;
  background: var(--color-surface-subtle);
  color: var(--color-text);
  cursor: pointer;
  font-family: inherit;
}

.unit-sheet-close:hover {
  background: var(--color-border);
}

.unit-sheet-close svg {
  width: 18px;
  height: 18px;
}

.unit-sheet-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 12px 16px 24px;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}

body.sheet-open {
  overflow: hidden;
}

.unit-btn {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
  padding: 12px 14px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  cursor: pointer;
  font-size: var(--font-size-sm);
  transition: all var(--transition);
  text-align: left;
  font-family: inherit;
  color: var(--color-text);
}

.unit-btn:hover {
  border-color: var(--color-primary);
  background: var(--color-primary-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.unit-btn.selected {
  border-color: var(--color-primary);
  background: var(--color-primary-bg);
}

.unit-btn.completed {
  border-color: var(--color-success);
}

.unit-btn.completed.selected {
  border-color: var(--color-success);
  background: var(--color-success-light);
}

.unit-btn.all-units {
  justify-content: center;
  font-weight: 700;
}

.unit-icon {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  background: var(--color-primary-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
}

.unit-btn.completed .unit-icon {
  background: var(--color-success-bg);
  color: var(--color-success);
}

.unit-icon svg {
  width: 18px;
  height: 18px;
}

.unit-icon.all-icon {
  background: linear-gradient(135deg, var(--color-primary-light), var(--color-primary-dark));
  color: var(--color-on-primary);
}

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

.unit-name {
  font-weight: 600;
  font-size: var(--font-size-sm);
  line-height: 1.3;
  margin-bottom: 6px;
}

.unit-meta {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
}

.unit-check-badge {
  flex-shrink: 0;
  color: var(--color-success);
}

.unit-check-badge svg {
  width: 20px;
  height: 20px;
}

.start-btn {
  display: block;
  width: 100%;
  background: linear-gradient(135deg, var(--color-primary-light), var(--color-primary-dark));
  color: var(--color-on-primary);
  border: none;
  padding: 16px;
  font-size: var(--font-size-md);
  border-radius: var(--radius-md);
  cursor: pointer;
  font-weight: 700;
  transition: transform var(--transition), box-shadow var(--transition), opacity var(--transition);
  font-family: inherit;
  box-shadow: 0 4px 14px rgba(46, 143, 181, 0.35);
}

.start-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(46, 143, 181, 0.4);
}

.start-btn:active {
  transform: translateY(0);
}

/* ===== STATIC PAGES ===== */
.page-card {
  background: var(--color-surface);
  border-radius: var(--radius-md);
  padding: 28px 24px;
  box-shadow: var(--shadow-sm);
  border: 2px solid var(--color-border);
  max-width: 560px;
  margin: 0 auto;
}

.page-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.page-icon {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background: var(--color-primary-bg);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
}

.page-icon svg {
  width: 22px;
  height: 22px;
}

.page-title {
  margin: 0;
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-text);
}

.page-text {
  margin: 0 0 14px;
  font-size: var(--font-size-base);
  color: var(--color-text-secondary);
  line-height: 1.55;
}

.page-note {
  margin: 0 0 20px;
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  line-height: 1.5;
}

.page-list {
  margin: 0 0 20px;
  padding-left: 20px;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.page-list li {
  margin-bottom: 6px;
}

.page-action-link {
  display: inline-block;
  font-size: var(--font-size-sm);
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
}

.page-action-link:hover {
  text-decoration: underline;
  text-underline-offset: 2px;
}

.page-action-link.is-pending {
  color: var(--color-muted);
  font-weight: 500;
  cursor: default;
  pointer-events: none;
}

.page-donate-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  background: #009ee3;
  color: var(--color-on-primary);
  font-size: var(--font-size-sm);
  font-weight: 700;
  text-decoration: none;
  transition: background var(--transition), opacity var(--transition);
}

.page-donate-btn:hover {
  background: #008ecf;
}

.page-donate-btn svg {
  width: 16px;
  height: 16px;
}

.page-donate-btn.is-pending {
  opacity: 0.45;
  cursor: not-allowed;
  pointer-events: none;
}

/* ===== QUIZ SCREEN ===== */
#quiz {
  display: none;
}

.quiz-header {
  background: var(--color-surface);
  border-radius: var(--radius-md);
  padding: 14px 18px;
  margin-bottom: 14px;
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 8px;
  z-index: 10;
}

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

.quiz-counter {
  font-weight: 700;
  font-size: var(--font-size-base);
}

.quiz-unit-label {
  font-size: var(--font-size-xs);
  color: var(--color-primary-dark);
  background: var(--color-primary-bg);
  padding: 4px 12px;
  border-radius: var(--radius-pill);
  font-weight: 600;
}

.progress-bar {
  height: 8px;
  background: var(--color-border);
  border-radius: 4px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary-light), var(--color-primary-dark));
  border-radius: 4px;
  transition: width 0.3s ease;
}

.question-card {
  background: var(--color-surface);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  margin-bottom: 14px;
}

.eliminatory-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: var(--color-error);
  color: var(--color-on-primary);
  font-size: var(--font-size-xs);
  font-weight: 700;
  padding: 4px 12px;
  border-radius: var(--radius-pill);
  margin-bottom: 14px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.question-text {
  font-size: var(--font-size-md);
  line-height: 1.5;
  margin-bottom: 16px;
  font-weight: 600;
}

.question-image-frame {
  background: var(--color-image-frame);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 16px;
  margin-bottom: 18px;
  text-align: center;
}

.question-image-media {
  position: relative;
  min-height: 220px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.question-image-skeleton {
  position: absolute;
  inset: 0;
  border-radius: var(--radius-sm);
  background: linear-gradient(
    90deg,
    var(--color-skeleton-a) 0%,
    var(--color-skeleton-b) 50%,
    var(--color-skeleton-a) 100%
  );
  background-size: 200% 100%;
  animation: questionImageShimmer 1.4s ease-in-out infinite;
}

.question-image-frame img {
  position: relative;
  z-index: 1;
  max-width: 100%;
  max-height: 220px;
  border-radius: var(--radius-sm);
  object-fit: contain;
  opacity: 0;
  transition: opacity 0.2s ease;
}

.question-image-frame.loaded img {
  opacity: 1;
}

.question-image-frame.loaded .question-image-skeleton {
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}

@keyframes questionImageShimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

@media (prefers-reduced-motion: reduce) {
  .question-image-skeleton {
    animation: none;
    background: var(--color-skeleton-a);
  }

  .question-image-frame img,
  .question-image-frame.loaded .question-image-skeleton {
    transition: none;
  }
}

.question-image-caption {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  margin-top: 10px;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.4px;
}

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

.option-btn {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  width: 100%;
  padding: 14px 16px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  cursor: pointer;
  font-size: var(--font-size-base);
  text-align: left;
  transition: all var(--transition);
  line-height: 1.4;
  font-family: inherit;
  color: var(--color-text);
}

.option-btn:hover {
  border-color: var(--color-primary);
  background: var(--color-primary-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.option-btn.selected {
  border-color: var(--color-primary);
  background: var(--color-primary-bg);
  font-weight: 600;
  box-shadow: 0 0 0 3px var(--color-focus-ring);
}

.option-letter {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--color-primary-bg);
  color: var(--color-primary-dark);
  font-weight: 700;
  font-size: var(--font-size-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
}

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

.option-text {
  flex: 1;
  padding-top: 2px;
}

.option-btn.revealed {
  cursor: default;
  transform: none;
  pointer-events: none;
}

.option-btn.revealed:hover {
  transform: none;
  box-shadow: none;
}

.option-btn.dimmed {
  opacity: 0.55;
}

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

.option-btn.correct .option-letter {
  background: var(--color-success);
  color: var(--color-on-primary);
}

.option-btn.incorrect {
  border-color: var(--color-error);
  background: var(--color-error-bg);
}

.option-btn.incorrect .option-letter {
  background: var(--color-error);
  color: var(--color-on-primary);
}

.option-letter svg {
  width: 16px;
  height: 16px;
}

.quiz-nav {
  display: flex;
  justify-content: space-between;
  gap: 12px;
}

.nav-btn {
  padding: 12px 28px;
  border: 2px solid var(--color-primary);
  border-radius: var(--radius-md);
  font-size: var(--font-size-base);
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
}

.nav-btn.prev {
  background: var(--color-surface);
  color: var(--color-primary);
}

.nav-btn.prev:hover {
  background: var(--color-primary-hover);
}

.nav-btn.next {
  background: var(--color-primary);
  color: var(--color-on-primary);
  margin-left: auto;
}

.nav-btn.next:hover {
  background: var(--color-primary-dark);
}

.nav-btn.submit {
  background: var(--color-success);
  color: var(--color-on-primary);
  border-color: var(--color-success);
  margin-left: auto;
}

.nav-btn.submit:hover {
  background: var(--color-success-hover);
}

.nav-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* ===== RESULTS SCREEN ===== */
#results {
  display: none;
  text-align: center;
  padding-top: 20px;
}

.results-card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 36px 28px;
  box-shadow: var(--shadow-md);
  margin-bottom: 24px;
  position: relative;
  overflow: hidden;
}

.results-card.is-pass::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 6px;
  background: linear-gradient(90deg, #2ecc71, var(--color-success));
}

.results-card.is-fail::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 6px;
  background: linear-gradient(90deg, #e57373, var(--color-error));
}

.score-circle {
  width: 160px;
  height: 160px;
  border-radius: 50%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  border: 6px solid;
  transition: transform 0.5s ease;
}

.results-card.is-pass .score-circle {
  animation: scorePop 0.5s ease;
}

@keyframes scorePop {
  0% { transform: scale(0.85); opacity: 0.5; }
  60% { transform: scale(1.05); }
  100% { transform: scale(1); opacity: 1; }
}

.score-circle.pass { border-color: var(--color-success); color: var(--color-success); }
.score-circle.fail { border-color: var(--color-error); color: var(--color-error); }

.score-number {
  font-size: var(--font-size-3xl);
  font-weight: 800;
  line-height: 1;
}

.score-label {
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-top: 4px;
  opacity: 0.85;
}

.result-status {
  font-size: var(--font-size-xl);
  font-weight: 800;
  margin-bottom: 8px;
  letter-spacing: 0.5px;
}

.result-status.pass { color: var(--color-success); }
.result-status.fail { color: var(--color-error); }

.result-detail {
  color: var(--color-text-secondary);
  margin-bottom: 6px;
  font-size: var(--font-size-base);
}

.eliminatory-fail {
  background: var(--color-error-bg);
  border: 1px solid var(--color-error);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  margin-top: 16px;
  color: var(--color-error-dark);
  font-weight: 500;
  text-align: left;
  font-size: var(--font-size-sm);
}

.review-section {
  text-align: left;
  margin-top: 24px;
  background: var(--color-surface);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
}

.review-section h3 {
  margin-bottom: 16px;
  font-size: var(--font-size-lg);
  font-weight: 700;
}

.review-toggle {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.review-toggle button {
  padding: 8px 16px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  cursor: pointer;
  font-size: var(--font-size-sm);
  transition: all var(--transition);
  font-family: inherit;
  font-weight: 500;
}

.review-toggle button:hover {
  border-color: var(--color-primary);
}

.review-toggle button.active {
  border-color: var(--color-primary);
  background: var(--color-primary-bg);
  font-weight: 700;
  color: var(--color-primary-dark);
}

.review-item {
  background: var(--color-surface-raised);
  border-radius: var(--radius-md);
  padding: 18px;
  margin-bottom: 12px;
  border-left: 4px solid;
  transition: box-shadow var(--transition);
}

.review-item:hover {
  box-shadow: var(--shadow-sm);
}

.review-item.correct-review { border-left-color: var(--color-success); }
.review-item.incorrect-review { border-left-color: var(--color-error); }

.review-item .review-unit {
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 6px;
  font-weight: 600;
}

.review-item .review-question {
  font-weight: 600;
  margin-bottom: 10px;
  font-size: var(--font-size-base);
  line-height: 1.45;
}

.review-item .review-image {
  text-align: center;
  margin-bottom: 10px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 10px;
}

.review-item .review-image img {
  max-width: 100%;
  max-height: 150px;
  border-radius: 4px;
}

.review-item .your-answer {
  color: var(--color-error);
  font-size: var(--font-size-sm);
  margin-bottom: 4px;
}

.review-item .correct-answer {
  color: var(--color-success);
  font-size: var(--font-size-sm);
  font-weight: 600;
}

.review-empty {
  text-align: center;
  color: var(--color-muted);
  padding: 24px;
  font-size: var(--font-size-sm);
}

.retry-btn {
  background: linear-gradient(135deg, var(--color-primary-light), var(--color-primary-dark));
  color: var(--color-on-primary);
  border: none;
  padding: 14px 40px;
  font-size: var(--font-size-base);
  border-radius: var(--radius-md);
  cursor: pointer;
  font-weight: 700;
  transition: transform var(--transition), box-shadow var(--transition);
  margin-top: 20px;
  font-family: inherit;
  box-shadow: 0 4px 14px rgba(46, 143, 181, 0.3);
}

.retry-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(46, 143, 181, 0.35);
}

/* ===== FOOTER ===== */
.site-footer {
  margin-top: auto;
  flex-shrink: 0;
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
}

.footer-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 20px 16px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  text-align: center;
}

.footer-credit {
  margin: 0;
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text);
}

.footer-divider {
  width: 100%;
  max-width: 280px;
  height: 1px;
  background: var(--color-border);
  margin: 4px 0;
}

.footer-source {
  margin: 0;
  font-size: var(--font-size-xs);
  color: var(--color-muted);
  line-height: 1.5;
}

.footer-link {
  color: var(--color-primary);
  font-weight: 600;
  text-decoration: none;
}

.footer-link:hover {
  text-decoration: underline;
  text-underline-offset: 2px;
}

/* ===== MODAL ===== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: var(--color-overlay);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 20px;
  animation: fadeIn 0.15s ease;
}

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

.modal-card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  max-width: 400px;
  width: 100%;
  box-shadow: var(--shadow-lg);
  animation: slideUp 0.2s ease;
}

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

.modal-message {
  font-size: var(--font-size-base);
  line-height: 1.5;
  color: var(--color-text);
  margin-bottom: 20px;
  text-align: center;
}

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

.modal-btn {
  padding: 10px 24px;
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
  border: none;
}

.modal-btn.primary {
  background: var(--color-primary);
  color: var(--color-on-primary);
}

.modal-btn.primary:hover {
  background: var(--color-primary-dark);
}

.modal-btn.secondary {
  background: var(--color-border);
  color: var(--color-modal-secondary-text);
}

.modal-btn.secondary:hover {
  background: var(--color-modal-secondary-hover);
}

/* ===== SCREEN TRANSITIONS ===== */
.screen-enter {
  animation: screenFadeIn 0.25s ease;
}

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

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* ===== RESPONSIVE ===== */
@media (max-width: 600px) {
  .container {
    padding: 12px;
  }

  .footer-inner {
    padding-left: 28px;
    padding-right: 28px;
  }

  .site-nav-link {
    padding: 8px 11px;
    font-size: 0.8rem;
  }

  .hero {
    padding: 18px 16px 22px;
  }

  .hero-title {
    font-size: 1.25rem;
  }

  .hero-subtitle {
    font-size: 0.8rem;
  }

  .resume-banner {
    flex-wrap: wrap;
    padding: 12px;
    gap: 10px;
  }

  .resume-actions {
    width: 100%;
    justify-content: flex-end;
  }

  .class-buttons {
    flex-direction: column;
    gap: 8px;
  }

  .class-btn {
    flex-direction: row;
    justify-content: flex-start;
    gap: 12px;
    padding: 10px 14px;
  }

  .class-btn-icon {
    width: 44px;
    height: 44px;
  }

  .class-btn-icon svg {
    width: 24px;
    height: 24px;
  }

  .class-btn-label {
    font-size: var(--font-size-sm);
    text-align: left;
  }

  .history-item-aside {
    display: contents;
  }

  .history-item {
    display: grid;
    grid-template-columns: 36px 1fr auto;
    grid-template-areas:
      "icon body score"
      "btn btn btn";
    gap: 10px;
    padding: 12px;
    align-items: start;
  }

  .history-item-icon {
    grid-area: icon;
    width: 36px;
    height: 36px;
  }

  .history-item-body {
    grid-area: body;
    min-width: 0;
  }

  .history-score {
    grid-area: score;
    font-size: 1.1rem;
    padding-top: 0;
  }

  .history-item-top {
    flex-direction: column;
    align-items: flex-start;
    gap: 5px;
    margin-bottom: 4px;
  }

  .history-item-label {
    font-size: 0.82rem;
  }

  .history-retake-btn {
    grid-area: btn;
    width: 100%;
    align-self: stretch;
    padding: 11px 16px;
    font-size: var(--font-size-sm);
  }

  .history-body.open .history-body-inner {
    padding: 16px 12px 18px;
  }

  .question-card {
    padding: 18px;
  }

  .question-text {
    font-size: var(--font-size-base);
  }

  .quiz-header {
    top: 4px;
    padding: 12px 14px;
  }

  .quiz-counter {
    font-size: var(--font-size-sm);
  }

  .score-circle {
    width: 130px;
    height: 130px;
  }

  .score-number {
    font-size: 2.2rem;
  }

  .review-section {
    padding: 18px;
  }

  .nav-btn {
    padding: 10px 20px;
    font-size: var(--font-size-sm);
  }
}

@media (min-width: 768px) {
  .unit-sheet-overlay {
    align-items: center;
    padding: 24px;
  }

  .unit-sheet {
    width: 100%;
    max-width: 860px;
    max-height: none;
    border-radius: var(--radius-lg);
    animation: sheetPopIn 0.22s ease;
  }

  .unit-sheet-handle {
    display: none;
  }

  .unit-sheet-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 10px;
    padding: 16px 20px 20px;
    overflow: visible;
  }

  .unit-sheet-list .unit-btn.all-units {
    grid-column: 1 / -1;
  }
}