@import url('https://fonts.googleapis.com/css2?family=Instrument+Serif:ital@0;1&family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500;600&display=swap');

:root {
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-serif: 'Instrument Serif', Georgia, serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  --bg-page: #fbfbfb;
  --bg-card: #ffffff;
  --bg-code: #1e1e2e;
  --text-main: #1d1d1f;
  --text-muted: #515154;
  --text-serif: #111111;
  --text-code: #cdd6f4;
  --accent: #8b5cf6;
  --accent-soft: #f0ebff;
  --accent-glow: rgba(139, 92, 246, 0.15);
  --border: #e5e5e7;
  --border-focus: #86868b;
  --success: #30d158;
  --success-soft: #eafbe7;
  --error: #ff453a;
  --error-soft: #ffebeb;
  --warning: #ffd60a;
  --warning-soft: #fff8e1;
  --radius: 12px;

  /* Code syntax colors (Catppuccin Mocha inspired) */
  --syn-keyword: #cba6f7;
  --syn-string: #a6e3a1;
  --syn-tag: #89b4fa;
  --syn-attr: #f9e2af;
  --syn-value: #a6e3a1;
  --syn-comment: #6c7086;
  --syn-punctuation: #9399b2;
  --syn-number: #fab387;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-page: #0a0a0f;
    --bg-card: #1c1c24;
    --bg-code: #11111b;
    --text-main: #f5f5f7;
    --text-muted: #86868b;
    --text-serif: #ffffff;
    --accent: #a78bfa;
    --accent-soft: #1a1528;
    --accent-glow: rgba(167, 139, 250, 0.2);
    --border: #2a2a35;
    --border-focus: #48484a;
    --success: #30d158;
    --success-soft: #142817;
    --error: #ff453a;
    --error-soft: #2c1414;
    --warning: #ffd60a;
    --warning-soft: #2c2a14;
  }
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-page);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  padding: 2rem 1.5rem;
}

.container {
  max-width: 760px;
  margin: 0 auto;
}

/* Header */
header {
  margin-bottom: 3rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 1.5rem;
}

.lesson-meta {
  font-size: 0.85rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 0.5rem;
  font-weight: 600;
}

.lesson-phase {
  display: inline-block;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.2rem 0.6rem;
  border-radius: 6px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.75rem;
}

h1 {
  font-family: var(--font-serif);
  font-size: 3.2rem;
  font-weight: 400;
  line-height: 1.1;
  color: var(--text-serif);
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
}

h2 {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 400;
  color: var(--text-serif);
  margin: 2.5rem 0 1rem 0;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.5rem;
}

h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-serif);
  margin: 1.5rem 0 0.75rem 0;
}

p {
  margin-bottom: 1.25rem;
  font-size: 1.05rem;
  color: var(--text-main);
}

ul,
ol {
  margin-bottom: 1.5rem;
  padding-left: 1.5rem;
}

li {
  margin-bottom: 0.5rem;
  font-size: 1.05rem;
}

a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

a:hover {
  text-decoration: underline;
}

code {
  font-family: var(--font-mono);
  background-color: var(--border);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  font-size: 0.88em;
}

blockquote {
  border-left: 3px solid var(--accent);
  padding-left: 1.25rem;
  margin: 1.5rem 0;
  color: var(--text-muted);
  font-style: italic;
}

/* KEY CONCEPT: A highlight box for critical takeaways */
.key-concept {
  background: linear-gradient(135deg, var(--accent-soft), transparent);
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin: 1.5rem 0;
  position: relative;
}

.key-concept::before {
  content: '💡';
  position: absolute;
  top: -12px;
  left: 16px;
  background: var(--bg-page);
  padding: 0 0.5rem;
  font-size: 1.2rem;
}

.key-concept h4 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--accent);
}

/* CODE BLOCK: Styled like a mini editor */
.code-block {
  background-color: var(--bg-code);
  border-radius: var(--radius);
  margin: 1.5rem 0;
  overflow: hidden;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.6rem 1rem;
  background-color: rgba(255, 255, 255, 0.04);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.code-block-dots {
  display: flex;
  gap: 6px;
}

.code-block-dots span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  display: inline-block;
}

.code-block-dots span:nth-child(1) {
  background-color: #ff5f56;
}
.code-block-dots span:nth-child(2) {
  background-color: #ffbd2e;
}
.code-block-dots span:nth-child(3) {
  background-color: #27c93f;
}

.code-block-filename {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: #6c7086;
  font-weight: 500;
}

.code-block pre {
  margin: 0;
  padding: 1.25rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--text-code);
  tab-size: 2;
}

.code-block pre code {
  background: none;
  padding: 0;
  border-radius: 0;
  font-size: inherit;
  color: inherit;
}

/* Syntax highlighting classes */
.syn-kw {
  color: var(--syn-keyword);
}
.syn-str {
  color: var(--syn-string);
}
.syn-tag {
  color: var(--syn-tag);
}
.syn-attr {
  color: var(--syn-attr);
}
.syn-val {
  color: var(--syn-value);
}
.syn-cmt {
  color: var(--syn-comment);
  font-style: italic;
}
.syn-punc {
  color: var(--syn-punctuation);
}
.syn-num {
  color: var(--syn-number);
}

/* OUTPUT BLOCK: Shows browser output */
.output-block {
  background-color: #ffffff;
  border: 2px solid var(--border);
  border-radius: var(--radius);
  margin: 1.5rem 0;
  overflow: hidden;
}

.output-block-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  background: var(--border);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.output-block-content {
  padding: 1.5rem;
  font-family: var(--font-sans);
}

@media (prefers-color-scheme: dark) {
  .output-block {
    background-color: var(--bg-card);
    border-color: var(--border);
  }
  .output-block-header {
    background: var(--border);
    color: var(--text-muted);
  }
}

/* VOCABULARY / CONCEPT BOX */
.vocabulary-box {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin: 1.5rem 0;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.02);
}

.vocabulary-box h4 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  color: var(--accent);
}

.vocabulary-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

@media (min-width: 480px) {
  .vocabulary-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.vocabulary-item {
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.5rem;
}

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

.word {
  font-weight: 700;
  color: var(--text-serif);
}

.meaning {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-top: 0.2rem;
}

/* PRACTICE ZONE */
.practice-zone {
  background-color: var(--accent-soft);
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  padding: 2rem;
  margin: 2.5rem 0;
}

.practice-zone h3 {
  color: var(--text-serif);
  margin-top: 0;
  font-family: var(--font-serif);
  font-size: 1.6rem;
  font-weight: 400;
}

/* QUIZ */
.quiz-container {
  margin-top: 1.5rem;
}

.quiz-question {
  font-weight: 600;
  margin-bottom: 1rem;
  font-size: 1.1rem;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.quiz-option {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-main);
  font-family: var(--font-sans);
  padding: 1rem;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 1rem;
  transition: all 0.2s ease;
  text-align: left;
  width: 100%;
  outline: none;
}

.quiz-option:hover:not(:disabled) {
  border-color: var(--accent);
  background-color: var(--accent-soft);
}

.quiz-option:disabled {
  cursor: not-allowed;
}

.quiz-option.correct {
  background-color: var(--success-soft);
  border-color: var(--success);
  color: var(--text-serif);
  font-weight: 600;
}

.quiz-option.incorrect {
  background-color: var(--error-soft);
  border-color: var(--error);
  color: var(--text-serif);
}

.quiz-feedback {
  margin-top: 1rem;
  padding: 1rem;
  border-radius: var(--radius);
  font-size: 0.95rem;
  display: none;
  font-weight: 500;
  line-height: 1.5;
}

.quiz-feedback.correct {
  display: block;
  background-color: var(--success-soft);
  color: var(--text-serif);
  border: 1px solid var(--success);
}

.quiz-feedback.incorrect {
  display: block;
  background-color: var(--error-soft);
  color: var(--text-serif);
  border: 1px solid var(--error);
}

/* Multi-step quiz */
.quiz-step {
  display: none;
}

.quiz-step.active {
  display: block;
}

.quiz-progress-bar {
  height: 6px;
  background-color: var(--border);
  border-radius: 3px;
  margin-bottom: 1.5rem;
  overflow: hidden;
}

.quiz-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), #c084fc);
  width: 0%;
  transition: width 0.3s ease;
}

.quiz-next-btn {
  background-color: var(--accent);
  color: #ffffff;
  border: none;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  cursor: pointer;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.95rem;
  margin-top: 1rem;
  transition: opacity 0.2s ease;
  display: none;
}

.quiz-next-btn:hover {
  opacity: 0.9;
}

.quiz-results-card {
  text-align: center;
  padding: 1.5rem;
}

.quiz-score-circle {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  border: 5px solid var(--accent);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--text-serif);
}

.quiz-retry-btn {
  background-color: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  cursor: pointer;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.95rem;
  margin-top: 1.5rem;
  transition: all 0.2s ease;
}

.quiz-retry-btn:hover {
  background-color: var(--accent-soft);
}

/* FILL-IN-THE-BLANK EXERCISE */
.fill-blank-exercise {
  margin: 1.5rem 0;
}

.fill-blank-line {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.fill-blank-line span {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--text-main);
}

.fill-blank-input {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  padding: 0.4rem 0.6rem;
  border: 2px dashed var(--border-focus);
  border-radius: 6px;
  background: var(--bg-card);
  color: var(--text-main);
  width: 160px;
  outline: none;
  transition: border-color 0.2s;
}

.fill-blank-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.fill-blank-input.correct {
  border-color: var(--success);
  border-style: solid;
  background-color: var(--success-soft);
}

.fill-blank-input.incorrect {
  border-color: var(--error);
  border-style: solid;
  background-color: var(--error-soft);
}

.fill-blank-check-btn {
  background-color: var(--accent);
  color: #fff;
  border: none;
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius);
  cursor: pointer;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.9rem;
  margin-top: 0.5rem;
  transition: opacity 0.2s;
}

.fill-blank-check-btn:hover {
  opacity: 0.9;
}

/* WARNING / TIP CALLOUT */
.callout {
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  margin: 1.5rem 0;
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--text-main);
}

.callout p, .callout li {
  color: var(--text-main);
}

.callout.tip {
  background: var(--success-soft);
  border: 1px solid var(--success);
  color: var(--text-main);
}

.callout.warning {
  background: var(--warning-soft);
  border: 1px solid var(--warning);
  color: var(--text-main);
}

.callout strong {
  display: block;
  margin-bottom: 0.25rem;
  color: var(--text-serif);
}

/* TABLE */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 1rem;
}

th,
td {
  border: 1px solid var(--border);
  padding: 0.75rem 1rem;
  text-align: left;
}

th {
  background-color: var(--border);
  font-weight: 600;
  color: var(--text-serif);
}

tr:nth-child(even) {
  background-color: rgba(0, 0, 0, 0.02);
}

/* NAVIGATION FOOTER */
.navigation-footer {
  margin-top: 4rem;
  border-top: 1px solid var(--border);
  padding-top: 1.5rem;
  display: flex;
  justify-content: space-between;
  font-size: 0.95rem;
}

.navigation-footer a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.navigation-footer a:hover {
  text-decoration: underline;
}

/* CSS PLAYGROUND: Live editor + preview */
.css-playground {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin: 1.5rem 0;
  overflow: hidden;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
}

.css-playground-editor {
  display: block;
  width: 100%;
  min-height: 140px;
  padding: 1.25rem;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--text-code);
  background-color: var(--bg-code);
  border: none;
  border-bottom: 1px solid var(--border);
  resize: vertical;
  outline: none;
  tab-size: 2;
}

.css-playground-editor:focus {
  box-shadow: inset 0 0 0 2px var(--accent-glow);
}

.css-playground-preview-wrapper {
  padding: 0;
}

.css-playground-label {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  padding: 0.6rem 1.25rem;
  border-bottom: 1px solid var(--border);
  background-color: rgba(0, 0, 0, 0.01);
}

.css-playground-preview {
  padding: 1.5rem;
  min-height: 80px;
}

.css-playground-reset {
  display: block;
  width: 100%;
  padding: 0.6rem;
  background-color: transparent;
  border: none;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}

.css-playground-reset:hover {
  background-color: var(--accent-soft);
  color: var(--accent);
}

/* FLEX PLAYGROUND: Interactive flex container editor */
.flex-playground {
  margin: 1.5rem 0;
}

.fp-wrapper {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-card);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
}

.fp-preview {
  padding: 1.5rem;
  min-height: 180px;
  background: var(--bg-page);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
}

.fp-flex-container {
  width: 100%;
  min-height: 140px;
  border: 2px dashed var(--accent);
  border-radius: 8px;
  padding: 12px;
  background: rgba(139, 92, 246, 0.03);
  transition: all 0.3s ease;
}

.fp-flex-item {
  color: #fff;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.1rem;
  padding: 16px 24px;
  border-radius: 6px;
  text-align: center;
  min-width: 48px;
  transition: all 0.3s ease;
}

.fp-bottom-panel {
  display: grid;
  grid-template-columns: 1fr 1fr;
}

@media (max-width: 600px) {
  .fp-bottom-panel {
    grid-template-columns: 1fr;
  }
}

.fp-controls {
  padding: 1.25rem;
  border-right: 1px solid var(--border);
}

.fp-controls-title {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.fp-control-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
}

.fp-control-label {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  font-weight: 600;
}

.fp-control-select {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  padding: 0.3rem 0.5rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg-page);
  color: var(--text-main);
  outline: none;
  cursor: pointer;
  min-width: 130px;
}

.fp-control-select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--accent-glow);
}

.fp-css-output {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.7;
  color: var(--text-code);
  background: var(--bg-code);
  margin: 0;
  padding: 1.25rem;
  white-space: pre;
  overflow-x: auto;
}

/* GRID PLAYGROUND: Interactive grid container editor */
.grid-playground {
  margin: 1.5rem 0;
}

.gp-wrapper {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-card);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
}

.gp-preview {
  padding: 1.5rem;
  min-height: 200px;
  background: var(--bg-page);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
}

.gp-grid-container {
  width: 100%;
  min-height: 160px;
  border: 2px dashed var(--accent);
  border-radius: 8px;
  padding: 12px;
  background: rgba(139, 92, 246, 0.03);
  transition: all 0.3s ease;
}

.gp-grid-item {
  color: #fff;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.1rem;
  padding: 16px 24px;
  border-radius: 6px;
  text-align: center;
  min-width: 48px;
  min-height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
}

.gp-bottom-panel {
  display: grid;
  grid-template-columns: 1fr 1fr;
}

@media (max-width: 600px) {
  .gp-bottom-panel {
    grid-template-columns: 1fr;
  }
}

.gp-controls {
  padding: 1.25rem;
  border-right: 1px solid var(--border);
}

.gp-controls-title {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.gp-control-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
  gap: 0.5rem;
}

.gp-control-label {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--accent);
  font-weight: 600;
  white-space: nowrap;
}

.gp-control-select {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  padding: 0.3rem 0.5rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg-page);
  color: var(--text-main);
  outline: none;
  cursor: pointer;
  min-width: 140px;
  max-width: 220px;
}

.gp-control-select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--accent-glow);
}

.gp-css-output {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.7;
  color: var(--text-code);
  background: var(--bg-code);
  margin: 0;
  padding: 1.25rem;
  white-space: pre;
  overflow-x: auto;
}

/* RESPONSIVE VIEWER: Interactive viewport-width preview */
.responsive-viewer {
  margin: 1.5rem 0;
}

.rv-wrapper {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-card);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
}

.rv-toolbar {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1.25rem;
  background: rgba(0, 0, 0, 0.02);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}

.rv-toolbar-label {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.rv-btn-group {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
}

.rv-btn {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  padding: 0.35rem 0.7rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg-page);
  color: var(--text-main);
  cursor: pointer;
  transition: all 0.2s ease;
  font-weight: 500;
}

.rv-btn:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.rv-btn.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  font-weight: 600;
}

.rv-preview-container {
  padding: 1.5rem;
  background: var(--bg-page);
  display: flex;
  justify-content: center;
  overflow-x: auto;
  min-height: 120px;
}

.rv-iframe {
  border: 2px dashed var(--accent);
  border-radius: 8px;
  background: #fff;
  transition: width 0.4s ease;
  display: block;
  max-width: 100%;
}

.rv-indicator {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--accent);
  text-align: center;
  padding: 0.6rem;
  border-top: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.02);
}

@media (prefers-color-scheme: dark) {
  .rv-iframe {
    background: var(--bg-card);
  }
}

/* JS PLAYGROUND: Live JavaScript console editor */
.js-playground {
  margin: 1.5rem 0;
}

.jsp-wrapper {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-card);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
}

.jsp-editor-row {
  display: flex;
  border-bottom: 1px solid var(--border);
}

.jsp-line-numbers {
  min-width: 44px;
  padding: 1.25rem 0.6rem 1.25rem 0;
  margin: 0;
  text-align: right;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--syn-comment);
  background-color: var(--bg-code);
  border-right: 1px solid rgba(255, 255, 255, 0.06);
  white-space: pre;
  overflow: hidden;
  user-select: none;
}

.jsp-editor {
  flex: 1;
  min-width: 0;
  display: block;
  width: 100%;
  min-height: 180px;
  padding: 1.25rem;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--text-code);
  background-color: var(--bg-code);
  border: none;
  resize: vertical;
  outline: none;
  tab-size: 2;
  white-space: pre;
  overflow-x: auto;
}

.jsp-editor:focus {
  box-shadow: inset 0 0 0 2px var(--accent-glow);
}

.jsp-toolbar {
  display: flex;
  gap: 0.5rem;
  padding: 0.6rem 1rem;
  background: rgba(0, 0, 0, 0.02);
  border-bottom: 1px solid var(--border);
}

.jsp-run-btn {
  background-color: var(--accent);
  color: #fff;
  border: none;
  padding: 0.4rem 1.1rem;
  border-radius: 6px;
  cursor: pointer;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.85rem;
  transition: opacity 0.2s ease;
}

.jsp-run-btn:hover {
  opacity: 0.9;
}

.jsp-reset-btn {
  background-color: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
  padding: 0.4rem 1rem;
  border-radius: 6px;
  cursor: pointer;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.85rem;
  transition: all 0.2s ease;
}

.jsp-reset-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background-color: var(--accent-soft);
}

.jsp-hint {
  margin-left: auto;
  align-self: center;
  font-size: 0.75rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.jsp-console {
  padding: 1.25rem;
  background-color: #14141c;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.7;
  min-height: 70px;
  max-height: 260px;
  overflow-y: auto;
}

@media (prefers-color-scheme: dark) {
  .jsp-console {
    background-color: #0d0d13;
  }
}

.jsp-console-label {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--syn-comment);
  margin-bottom: 0.5rem;
}

.js-console-line {
  color: #cdd6f4;
  white-space: pre-wrap;
  word-break: break-word;
}

.js-console-error {
  color: var(--error);
}

/* PRINT */
@media print {
  body {
    background-color: #fff;
    color: #000;
    padding: 0;
  }
  .container {
    max-width: 100%;
  }
  .practice-zone {
    background-color: #fff;
    border: 1px solid #000;
    page-break-inside: avoid;
  }
  .quiz-option {
    border: 1px solid #000;
  }
  .code-block {
    page-break-inside: avoid;
  }
}