:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --bg-hover: #30363d;
  --border-primary: #30363d;
  --border-active: #58a6ff;
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --accent-blue: #58a6ff;
  --accent-green: #3fb950;
  --accent-yellow: #d29922;
  --accent-red: #f85149;
  --accent-purple: #a371f7;
  --accent-orange: #f0883e;
  --code-bg: #0d1117;
  --code-border: #30363d;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.5);
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'SF Mono', monospace;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: var(--accent-blue);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: #79b8ff;
  text-decoration: underline;
}

code, pre, kbd, samp {
  font-family: var(--font-mono);
  font-size: 0.9em;
}

.pre-wrap {
  white-space: pre-wrap;
  word-break: break-word;
}

.nowrap {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 48px 0;
  border-bottom: 1px solid var(--border-primary);
}

.section:last-child {
  border-bottom: none;
}

.section-title {
  font-size: 1.75rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.section-subtitle {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 800px;
}

.card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-md);
  padding: 24px;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

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

.card-title {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 2px 8px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  color: var(--text-secondary);
}

.badge-blue { background: rgba(88, 166, 255, 0.15); color: var(--accent-blue); }
.badge-green { background: rgba(63, 185, 80, 0.15); color: var(--accent-green); }
.badge-yellow { background: rgba(210, 153, 34, 0.15); color: var(--accent-yellow); }
.badge-red { background: rgba(248, 81, 73, 0.15); color: var(--accent-red); }
.badge-purple { background: rgba(163, 113, 247, 0.15); color: var(--accent-purple); }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.btn-primary {
  background: var(--accent-blue);
  color: #fff;
  border-color: var(--accent-blue);
}

.btn-primary:hover {
  background: #3a8ae6;
  border-color: #3a8ae6;
  color: #fff;
  text-decoration: none;
}

.btn-secondary {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border-color: var(--border-primary);
}

.btn-secondary:hover {
  background: var(--bg-hover);
  border-color: var(--border-active);
  color: var(--text-primary);
  text-decoration: none;
}

.btn-danger {
  background: var(--accent-red);
  color: #fff;
  border-color: var(--accent-red);
}

.btn-danger:hover {
  background: #e03e3e;
  border-color: #e03e3e;
  color: #fff;
  text-decoration: none;
}

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

.btn-ghost:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  text-decoration: none;
}

.btn-sm {
  padding: 6px 12px;
  font-size: 0.8125rem;
}

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

.input {
  width: 100%;
  padding: 10px 12px;
  font-size: 0.875rem;
  font-family: var(--font-mono);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.input:focus {
  outline: none;
  border-color: var(--border-active);
  box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.15);
}

.input::placeholder {
  color: var(--text-muted);
}

.textarea {
  min-height: 120px;
  resize: vertical;
  font-family: var(--font-mono);
}

.label {
  display: block;
  font-size: 0.8125rem;
  font-weight: 500;
  margin-bottom: 6px;
  color: var(--text-secondary);
}

.form-group {
  margin-bottom: 16px;
}

.grid {
  display: grid;
  gap: 24px;
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 1024px) {
  .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

.flex { display: flex; }
.flex-1 { flex: 1; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-8 { gap: 8px; }
.gap-12 { gap: 12px; }
.gap-16 { gap: 16px; }
.gap-24 { gap: 24px; }

.mt-8 { margin-top: 8px; }
.mt-16 { margin-top: 16px; }
.mt-24 { margin-top: 24px; }
.mt-32 { margin-top: 32px; }
.mb-8 { margin-bottom: 8px; }
.mb-16 { margin-bottom: 16px; }
.mb-24 { margin-bottom: 24px; }

.code-block {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  position: relative;
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  background: var(--bg-tertiary);
  border-bottom: 1px solid var(--code-border);
  font-size: 0.75rem;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

.code-block-lang {
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

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

.code-block-btn {
  padding: 4px 10px;
  font-size: 0.7rem;
  background: transparent;
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.code-block-btn:hover {
  background: var(--bg-hover);
  border-color: var(--border-active);
  color: var(--text-primary);
}

.code-block pre {
  margin: 0;
  padding: 16px;
  overflow-x: auto;
  line-height: 1.7;
}

.code-block code {
  font-size: 0.8125rem;
  line-height: inherit;
  color: var(--text-primary);
}

.token.comment { color: #6a737d; }
.token.prolog { color: #6a737d; }
.token.doctype { color: #6a737d; }
.token.cdata { color: #6a737d; }
.token.punctuation { color: #c9d1d9; }
.token.namespace { opacity: 0.7; }
.token.property { color: #79c0ff; }
.token.tag { color: #f97583; }
.token.boolean { color: #79c0ff; }
.token.number { color: #79c0ff; }
.token.constant { color: #79c0ff; }
.token.symbol { color: #79c0ff; }
.token.deleted { color: #f85149; }
.token.selector { color: #d2a8ff; }
.token.attr-name { color: #d2a8ff; }
.token.string { color: #a5d6ff; }
.token.char { color: #a5d6ff; }
.token.builtin { color: #79c0ff; }
.token.inserted { color: #3fb950; }
.token.operator { color: #c9d1d9; }
.token.entity { color: #c9d1d9; cursor: help; }
.token.url { color: #a5d6ff; }
.token.variable { color: #ffa657; }
.token.atrule { color: #d2a8ff; }
.token.attr-value { color: #a5d6ff; }
.token.function { color: #d2a8ff; }
.token.class-name { color: #d2a8ff; }
.token.regex { color: #a5d6ff; }
.token.important { color: #f85149; font-weight: bold; }
.token.bold { font-weight: bold; }
.token.italic { font-style: italic; }
.token.keyword { color: #ff7b72; }
.token.modifier { color: #ff7b72; }
.token.control { color: #ff7b72; }
.token.directive { color: #d2a8ff; }
.token.generic { color: #c9d1d9; }

.inline-code {
  background: var(--bg-tertiary);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  font-size: 0.85em;
  border: 1px solid var(--border-primary);
}

.table-wrapper {
  overflow-x: auto;
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-md);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

th, td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border-primary);
}

th {
  background: var(--bg-tertiary);
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
  position: sticky;
  top: 0;
  z-index: 1;
}

tr:last-child td {
  border-bottom: none;
}

tr:hover td {
  background: var(--bg-tertiary);
}

.code-diff {
  display: flex;
  gap: 1px;
}

.code-diff > div {
  flex: 1;
}

.code-diff pre {
  margin: 0;
}

.code-diff .diff-remove {
  background: rgba(248, 81, 73, 0.1);
  border-right: 1px solid var(--border-primary);
}

.code-diff .diff-add {
  background: rgba(63, 185, 80, 0.1);
}

.code-diff .diff-line {
  display: block;
  padding: 4px 16px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.6;
  white-space: pre;
}

.diff-line.removed { color: #ffa198; }
.diff-line.added { color: #7ee787; }
.diff-line.unchanged { color: var(--text-secondary); }

.tabs {
  display: flex;
  border-bottom: 1px solid var(--border-primary);
  margin-bottom: 16px;
  overflow-x: auto;
}

.tab-btn {
  padding: 10px 16px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

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

.tab-btn.active {
  color: var(--accent-blue);
  border-bottom-color: var(--accent-blue);
}

.tab-panel {
  display: none;
}

.tab-panel.active {
  display: block;
  animation: fadeIn 0.2s ease;
}

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

.accordion {
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.accordion-item {
  border-bottom: 1px solid var(--border-primary);
}

.accordion-item:last-child {
  border-bottom: none;
}

.accordion-header {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  background: var(--bg-secondary);
  border: none;
  color: var(--text-primary);
  font-size: 0.9375rem;
  font-weight: 500;
  text-align: left;
  cursor: pointer;
  transition: background var(--transition-fast);
}

.accordion-header:hover {
  background: var(--bg-tertiary);
}

.accordion-icon {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  transition: transform var(--transition-fast);
  color: var(--text-secondary);
}

.accordion-item.open .accordion-icon {
  transform: rotate(180deg);
}

.accordion-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease-out;
}

.accordion-item.open .accordion-content {
  max-height: 2000px;
  transition: max-height 0.5s ease-in;
}

.accordion-body {
  padding: 20px;
  background: var(--bg-primary);
}

.alert {
  padding: 16px 20px;
  border-radius: var(--radius-md);
  border-left: 4px solid;
  margin-bottom: 16px;
}

.alert-info {
  background: rgba(88, 166, 255, 0.1);
  border-color: var(--accent-blue);
  color: #a5d6ff;
}

.alert-success {
  background: rgba(63, 185, 80, 0.1);
  border-color: var(--accent-green);
  color: #7ee787;
}

.alert-warning {
  background: rgba(210, 153, 34, 0.1);
  border-color: var(--accent-yellow);
  color: #e3b341;
}

.alert-danger {
  background: rgba(248, 81, 73, 0.1);
  border-color: var(--accent-red);
  color: #ffa198;
}

.tooltip {
  position: relative;
  display: inline-block;
  cursor: help;
}

.tooltip::before {
  content: attr(data-tooltip);
  position: absolute;
  bottom: 125%;
  left: 50%;
  transform: translateX(-50%);
  padding: 8px 12px;
  font-size: 0.75rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  white-space: nowrap;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-fast);
  z-index: 100;
  box-shadow: var(--shadow-md);
}

.tooltip::after {
  content: '';
  position: absolute;
  bottom: 115%;
  left: 50%;
  transform: translateX(-50%);
  border: 6px solid transparent;
  border-top-color: var(--border-primary);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-fast);
}

.tooltip:hover::before,
.tooltip:hover::after {
  opacity: 1;
  visibility: visible;
}

.progress-bar {
  height: 6px;
  background: var(--bg-tertiary);
  border-radius: 3px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--accent-blue);
  border-radius: 3px;
  transition: width 0.3s ease;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.breadcrumb a { color: var(--text-secondary); }
.breadcrumb a:hover { color: var(--accent-blue); }
.breadcrumb .current { color: var(--text-primary); font-weight: 500; }

.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;
}

.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  padding: 8px 16px;
  background: var(--accent-blue);
  color: #fff;
  z-index: 1000;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 0;
}

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.8);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
}

.modal-overlay.open {
  opacity: 1;
  visibility: visible;
}

.modal {
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  max-width: 900px;
  width: 100%;
  max-height: 85vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transform: scale(0.95);
  transition: transform var(--transition-normal);
}

.modal-overlay.open .modal {
  transform: scale(1);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  border-bottom: 1px solid var(--border-primary);
}

.modal-title {
  font-size: 1.125rem;
  font-weight: 600;
}

.modal-close {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.modal-close:hover {
  background: var(--bg-tertiary);
  border-color: var(--border-active);
  color: var(--text-primary);
}

.modal-body {
  padding: 24px;
  overflow-y: auto;
}

.modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  padding: 16px 24px;
  border-top: 1px solid var(--border-primary);
  background: var(--bg-tertiary);
}

.skeleton {
  background: linear-gradient(90deg, var(--bg-tertiary) 25%, var(--bg-hover) 50%, var(--bg-tertiary) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius-sm);
}

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

.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;
}

@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;
  }
}

@media print {
  .no-print { display: none !important; }
  body { background: #fff; color: #000; }
  .card { box-shadow: none; border: 1px solid #ddd; }
}

/* ============ Missing utility classes ============ */
.w-20 { width: 20px; }
.h-20 { height: 20px; }
.w-64 { width: 64px; }
.h-64 { height: 64px; }
.h-full { height: 100%; }
.block { display: block; }
.flex-shrink-0 { flex-shrink: 0; }
.flex-wrap { flex-wrap: wrap; }
.items-start { align-items: flex-start; }
.justify-center { justify-content: center; }
.text-center { text-align: center; }
.mx-auto { margin-left: auto; margin-right: auto; }
.ml-8 { margin-left: 8px; }
.mt-4 { margin-top: 4px; }
.mt-12 { margin-top: 12px; }
.mb-4 { margin-bottom: 4px; }
.mb-12 { margin-bottom: 12px; }
.mb-32 { margin-bottom: 32px; }
.px-8 { padding-left: 8px; padding-right: 8px; }
.py-4 { padding-top: 4px; padding-bottom: 4px; }
.py-24 { padding-top: 24px; padding-bottom: 24px; }
.py-48 { padding-top: 48px; padding-bottom: 48px; }
.pt-16 { padding-top: 16px; }
.p-12 { padding: 12px; }
.p-16 { padding: 16px; }
.gap-4 { gap: 4px; }
.overflow-auto { overflow: auto; }
.overflow-x-auto { overflow-x: auto; }
.rounded-md { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-full { border-radius: 9999px; }
.border { border: 1px solid var(--border-primary); }
.border-2 { border: 2px solid var(--border-primary); }
.border-t { border-top: 1px solid var(--border-primary); }
.border-border-primary { border-color: var(--border-primary); }
.border-accent-blue { border-color: var(--accent-blue); }
.border-accent-green { border-color: var(--accent-green); }
.border-accent-red { border-color: var(--accent-red); }
.border-accent-blue\/20 { border-color: rgba(88, 166, 255, 0.2); }
.border-accent-green\/20 { border-color: rgba(63, 185, 80, 0.2); }
.bg-bg-tertiary { background: var(--bg-tertiary); }
.bg-accent-blue { background: var(--accent-blue); }
.bg-accent-blue\/10 { background: rgba(88, 166, 255, 0.1); }
.bg-blue-500\/10 { background: rgba(88, 166, 255, 0.1); }
.bg-green-500\/10 { background: rgba(63, 185, 80, 0.1); }
.text-xs { font-size: 0.75rem; }
.text-sm { font-size: 0.875rem; }
.text-lg { font-size: 1.125rem; }
.text-xl { font-size: 1.25rem; }
.text-2xl { font-size: 1.5rem; }
.text-3xl { font-size: 1.875rem; }
.text-4xl { font-size: 2.25rem; }
.font-bold { font-weight: 700; }
.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-mono { font-family: var(--font-mono); }
.text-text-primary { color: var(--text-primary); }
.text-text-secondary { color: var(--text-secondary); }
.text-accent-blue { color: var(--accent-blue); }
.text-accent-green { color: var(--accent-green); }
.text-accent-red { color: var(--accent-red); }
.text-accent-purple { color: var(--accent-purple); }
.text-accent-yellow { color: var(--accent-yellow); }
.text-decoration-none { text-decoration: none; }
.cursor-pointer { cursor: pointer; }
.transition-all { transition: all var(--transition-fast); }
.transition-colors { transition: color var(--transition-fast), background-color var(--transition-fast), border-color var(--transition-fast); }
.max-w-2xl { max-width: 42rem; }
.max-w-3xl { max-width: 48rem; }
.max-w-none { max-width: none; }
.space-y-8 > * + * { margin-top: 8px; }
.space-y-16 > * + * { margin-top: 16px; }
.space-y-24 > * + * { margin-top: 24px; }
.hover\:border-accent-blue:hover { border-color: var(--accent-blue); }
.hover\:text-text-primary:hover { color: var(--text-primary); }
.hover\:text-accent-red:hover { color: var(--accent-red); }
.hidden { display: none; }
.md\:flex { display: flex; }
@media (max-width: 768px) {
  .hidden { display: none; }
}
.btn-lg { padding: 12px 24px; font-size: 1.0625rem; }
.badge-orange { background: rgba(240, 136, 62, 0.15); color: var(--accent-orange); }

/* ============ MCQ components ============ */
.mcq-container { max-width: 100%; }
.mcq-progress { margin-bottom: 24px; }
.mcq-question-card { padding: 28px; }
.mcq-question-meta { display: flex; flex-wrap: wrap; gap: 8px; }
.mcq-question-text { font-size: 1.25rem; line-height: 1.5; }
.mcq-options { display: flex; flex-direction: column; gap: 12px; }

.mcq-option {
  display: block;
  padding: 16px;
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: border-color var(--transition-fast), background var(--transition-fast);
}
.mcq-option:hover { border-color: var(--accent-blue); }
.mcq-option:focus-visible { outline: 2px solid var(--accent-blue); outline-offset: 2px; }
.mcq-option.selected-option {
  border-color: var(--accent-blue);
  background: rgba(88, 166, 255, 0.1);
}

.mcq-option-marker {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  border: 2px solid var(--border-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 2px;
  transition: border-color var(--transition-fast), background var(--transition-fast);
}
.mcq-option-marker.selected {
  border-color: var(--accent-blue);
  background: var(--accent-blue);
}
.mcq-option-text { color: var(--text-primary); line-height: 1.55; }

.mcq-feedback { border: 1px solid; }
.mcq-feedback.alert-success { border-color: rgba(63, 185, 80, 0.4); }
.mcq-feedback.alert-danger { border-color: rgba(248, 81, 73, 0.4); }

.mcq-actions { display: flex; justify-content: space-between; align-items: center; margin-top: 24px; }
.mcq-complete { text-align: center; padding: 48px 0; }

/* ============ Coding task components ============ */
.coding-task-header { margin-bottom: 24px; }
.coding-task-description { margin-bottom: 16px; }
.coding-hints { margin-top: 16px; }
.coding-hints summary { cursor: pointer; color: var(--text-secondary); font-weight: 500; }
.coding-hints summary:hover { color: var(--text-primary); }
.coding-editor-wrapper { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; align-items: stretch; }
.coding-editor-panel, .coding-output-panel { min-width: 0; }
.coding-output-content { flex: 1; overflow: auto; padding: 16px; font-family: var(--font-mono); font-size: 0.875rem; white-space: pre-wrap; word-break: break-word; }
.coding-test-cases { margin-top: 24px; }
.coding-test-cases summary { cursor: pointer; font-weight: 500; }
.coding-navigation { display: flex; justify-content: space-between; margin-top: 24px; padding-top: 16px; border-top: 1px solid var(--border-primary); }
.coding-complete { text-align: center; padding: 48px 0; }

tr.test-passed td { background: rgba(63, 185, 80, 0.08); }
tr.test-passed td:last-child { color: var(--accent-green); font-weight: 600; }
tr.test-failed td { background: rgba(248, 81, 73, 0.08); }
tr.test-failed td:last-child { color: var(--accent-red); font-weight: 600; }

/* Toast used by coding-tasks */
.fixed { position: fixed; }
.bottom-24 { bottom: 24px; }
.right-24 { right: 24px; }
.z-100 { z-index: 100; }
.shadow-lg { box-shadow: var(--shadow-lg); }
.animate-slide-up { animation: slide-up 0.3s ease; }
@keyframes slide-up {
  from { transform: translateY(16px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

/* Markdown rendering (prose) */
.prose { color: var(--text-primary); line-height: 1.7; }
.prose h1 { font-size: 1.5rem; font-weight: 700; margin: 16px 0 8px; }
.prose h2 { font-size: 1.25rem; font-weight: 700; margin: 16px 0 8px; }
.prose h3 { font-size: 1.125rem; font-weight: 600; margin: 16px 0 8px; }
.prose p { margin: 8px 0; }
.prose li { margin: 4px 0 4px 20px; }
.prose strong { color: var(--text-primary); }
.prose code { background: var(--bg-tertiary); padding: 2px 6px; border-radius: var(--radius-sm); font-size: 0.85em; border: 1px solid var(--border-primary); }
.prose-invert { color: var(--text-primary); }

/* ============ Module page structural classes ============ */
.site-header, .module-header { display: flex; align-items: center; }
.site-footer { padding: 32px 0; border-top: 1px solid var(--border-primary); text-align: center; color: var(--text-secondary); }
.hero-section { padding: 32px 0; border-bottom: 1px solid var(--border-primary); }
.section-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 24px; }
.with-without { display: flex; gap: 16px; flex-wrap: wrap; }
.hook-section { margin-bottom: 32px; }

/* Responsive collapse for coding editor split */
@media (max-width: 760px) {
  .coding-editor-wrapper { grid-template-columns: 1fr; }
}