/* ============================================
   DATA ENGINEERING QUEST — STYLE SYSTEM
   Dark-first data-lab palette
   ============================================ */

/* --- DESIGN TOKENS --- */
:root {
  --text-xs: clamp(0.7rem, 0.65rem + 0.25vw, 0.8rem);
  --text-sm: clamp(0.8rem, 0.75rem + 0.25vw, 0.875rem);
  --text-base: clamp(0.9375rem, 0.9rem + 0.2vw, 1rem);
  --text-lg: clamp(1.05rem, 0.95rem + 0.5vw, 1.25rem);
  --text-xl: clamp(1.25rem, 1.1rem + 0.75vw, 1.75rem);
  --text-2xl: clamp(1.6rem, 1.2rem + 1.5vw, 2.5rem);
  --text-3xl: clamp(2rem, 1.2rem + 2.5vw, 3.25rem);

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-code: 'JetBrains Mono', 'SF Mono', 'Cascadia Code', 'Fira Code', monospace;

  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  --transition-fast: 150ms cubic-bezier(0.16, 1, 0.3, 1);
  --transition-med: 250ms cubic-bezier(0.16, 1, 0.3, 1);
  --transition-slow: 400ms cubic-bezier(0.16, 1, 0.3, 1);

  --sidebar-width: 280px;
  --header-height: 56px;
  --content-max: 860px;
}

/* --- DARK THEME (DEFAULT) --- */
[data-theme="dark"] {
  --color-bg: #0d1117;
  --color-surface: #141a22;
  --color-surface-2: #1a2230;
  --color-surface-3: #212b3b;
  --color-border: #2a3545;
  --color-border-2: #354155;
  --color-text: #e0e4ea;
  --color-text-muted: #8b95a5;
  --color-text-faint: #5a6577;
  --color-accent: #22d3c5;
  --color-accent-dim: rgba(34, 211, 197, 0.12);
  --color-accent-2: #3b9eff;
  --color-accent-2-dim: rgba(59, 158, 255, 0.12);
  --color-accent-3: #10b981;
  --color-accent-3-dim: rgba(16, 185, 129, 0.12);
  --color-xp: #facc15;
  --color-xp-dim: rgba(250, 204, 21, 0.12);
  --color-error: #f87171;
  --color-error-dim: rgba(248, 113, 113, 0.12);
  --color-warning: #fbbf24;
  --color-success: #34d399;
  --color-purple: #a78bfa;
  --color-purple-dim: rgba(167, 139, 250, 0.12);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.5);
  --code-bg: #0b1018;
  --code-border: #1e2a3a;
  --code-keyword: #c084fc;
  --code-string: #34d399;
  --code-number: #fbbf24;
  --code-comment: #5a6577;
  --code-func: #60a5fa;
  --code-builtin: #22d3c5;
  --code-operator: #e0e4ea;
  --code-class: #f59e0b;
  --code-decorator: #fb923c;
  --code-param: #f0abfc;
  --callout-tip-bg: rgba(34, 211, 197, 0.08);
  --callout-tip-border: rgba(34, 211, 197, 0.3);
  --callout-warn-bg: rgba(251, 191, 36, 0.08);
  --callout-warn-border: rgba(251, 191, 36, 0.3);
  --callout-mistake-bg: rgba(248, 113, 113, 0.08);
  --callout-mistake-border: rgba(248, 113, 113, 0.3);
  --callout-info-bg: rgba(59, 158, 255, 0.08);
  --callout-info-border: rgba(59, 158, 255, 0.3);
}

/* --- LIGHT THEME --- */
[data-theme="light"] {
  --color-bg: #f4f6f9;
  --color-surface: #ffffff;
  --color-surface-2: #f0f2f6;
  --color-surface-3: #e8ecf1;
  --color-border: #d5dbe5;
  --color-border-2: #c0c9d6;
  --color-text: #1a2332;
  --color-text-muted: #5a6577;
  --color-text-faint: #8b95a5;
  --color-accent: #0d9488;
  --color-accent-dim: rgba(13, 148, 136, 0.1);
  --color-accent-2: #2563eb;
  --color-accent-2-dim: rgba(37, 99, 235, 0.1);
  --color-accent-3: #059669;
  --color-accent-3-dim: rgba(5, 150, 105, 0.1);
  --color-xp: #ca8a04;
  --color-xp-dim: rgba(202, 138, 4, 0.1);
  --color-error: #dc2626;
  --color-error-dim: rgba(220, 38, 38, 0.08);
  --color-warning: #d97706;
  --color-success: #059669;
  --color-purple: #7c3aed;
  --color-purple-dim: rgba(124, 58, 237, 0.08);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.12);
  --code-bg: #f8fafc;
  --code-border: #e2e8f0;
  --code-keyword: #7c3aed;
  --code-string: #059669;
  --code-number: #d97706;
  --code-comment: #94a3b8;
  --code-func: #2563eb;
  --code-builtin: #0d9488;
  --code-operator: #374151;
  --code-class: #b45309;
  --code-decorator: #ea580c;
  --code-param: #a855f7;
  --callout-tip-bg: rgba(13, 148, 136, 0.06);
  --callout-tip-border: rgba(13, 148, 136, 0.3);
  --callout-warn-bg: rgba(217, 119, 6, 0.06);
  --callout-warn-border: rgba(217, 119, 6, 0.3);
  --callout-mistake-bg: rgba(220, 38, 38, 0.06);
  --callout-mistake-border: rgba(220, 38, 38, 0.3);
  --callout-info-bg: rgba(37, 99, 235, 0.06);
  --callout-info-border: rgba(37, 99, 235, 0.3);
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme]) {
    --color-bg: #f4f6f9;
    --color-surface: #ffffff;
    --color-surface-2: #f0f2f6;
    --color-surface-3: #e8ecf1;
    --color-border: #d5dbe5;
    --color-border-2: #c0c9d6;
    --color-text: #1a2332;
    --color-text-muted: #5a6577;
    --color-text-faint: #8b95a5;
    --color-accent: #0d9488;
    --color-accent-dim: rgba(13, 148, 136, 0.1);
    --color-accent-2: #2563eb;
    --color-accent-2-dim: rgba(37, 99, 235, 0.1);
    --color-accent-3: #059669;
    --color-accent-3-dim: rgba(5, 150, 105, 0.1);
    --color-xp: #ca8a04;
    --color-xp-dim: rgba(202, 138, 4, 0.1);
    --color-error: #dc2626;
    --color-error-dim: rgba(220, 38, 38, 0.08);
    --color-warning: #d97706;
    --color-success: #059669;
    --color-purple: #7c3aed;
    --color-purple-dim: rgba(124, 58, 237, 0.08);
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
    --shadow-lg: 0 12px 40px rgba(0,0,0,0.12);
    --code-bg: #f8fafc;
    --code-border: #e2e8f0;
    --code-keyword: #7c3aed;
    --code-string: #059669;
    --code-number: #d97706;
    --code-comment: #94a3b8;
    --code-func: #2563eb;
    --code-builtin: #0d9488;
    --code-operator: #374151;
    --code-class: #b45309;
    --code-decorator: #ea580c;
    --code-param: #a855f7;
    --callout-tip-bg: rgba(13, 148, 136, 0.06);
    --callout-tip-border: rgba(13, 148, 136, 0.3);
    --callout-warn-bg: rgba(217, 119, 6, 0.06);
    --callout-warn-border: rgba(217, 119, 6, 0.3);
    --callout-mistake-bg: rgba(220, 38, 38, 0.06);
    --callout-mistake-border: rgba(220, 38, 38, 0.3);
    --callout-info-bg: rgba(37, 99, 235, 0.06);
    --callout-info-border: rgba(37, 99, 235, 0.3);
  }
}

/* --- BASE RESET --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + var(--space-8));
}
body {
  min-height: 100dvh;
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg);
  overflow-x: hidden;
}
img, svg { display: block; max-width: 100%; }
ul[role='list'], ol[role='list'] { list-style: none; }
input, button, textarea, select { font: inherit; color: inherit; }
h1, h2, h3, h4, h5, h6 { text-wrap: balance; line-height: 1.2; }
p, li, figcaption { text-wrap: pretty; }
a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; }
::selection { background: rgba(34, 211, 197, 0.25); color: var(--color-text); }
:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; border-radius: var(--radius-sm); }
button { cursor: pointer; background: none; border: none; }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; scroll-behavior: auto !important; } }

.skip-link {
  position: absolute; top: -100px; left: 16px; z-index: 9999;
  padding: var(--space-2) var(--space-4); background: var(--color-accent); color: #000;
  border-radius: var(--radius-md); font-weight: 600; font-size: var(--text-sm);
}
.skip-link:focus { top: 8px; }

/* --- HEADER --- */
.header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: var(--header-height);
  background: color-mix(in srgb, var(--color-bg) 85%, transparent);
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: var(--header-height); padding: 0 var(--space-4);
  max-width: 100%;
}
.header-left { display: flex; align-items: center; gap: var(--space-3); }
.header-center { flex: 1; display: flex; justify-content: center; }
.header-right { display: flex; align-items: center; gap: var(--space-3); }

.menu-toggle {
  display: none; color: var(--color-text-muted); padding: var(--space-1);
  border-radius: var(--radius-sm);
}
.menu-toggle:hover { color: var(--color-text); background: var(--color-surface-2); }

.logo { display: flex; align-items: center; gap: var(--space-2); }
.logo-text {
  font-size: var(--text-lg); font-weight: 700;
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent-2));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}

.search-trigger {
  display: flex; align-items: center; gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-full); color: var(--color-text-muted);
  font-size: var(--text-sm); min-width: 240px; transition: all var(--transition-fast);
}
.search-trigger:hover { border-color: var(--color-border-2); color: var(--color-text); }
.search-trigger kbd {
  margin-left: auto; padding: 1px 6px; font-size: var(--text-xs);
  background: var(--color-surface-2); border: 1px solid var(--color-border);
  border-radius: 4px; font-family: var(--font-body); color: var(--color-text-faint);
}

.xp-display {
  display: flex; align-items: center; gap: var(--space-1);
  padding: var(--space-1) var(--space-3); background: var(--color-xp-dim);
  border-radius: var(--radius-full); font-size: var(--text-sm); font-weight: 600;
  color: var(--color-xp);
}
.level-badge {
  display: flex; align-items: center; gap: var(--space-1);
  padding: var(--space-1) var(--space-3); background: var(--color-accent-dim);
  border-radius: var(--radius-full); font-size: var(--text-sm); font-weight: 500;
  color: var(--color-accent);
}
.level-icon { font-size: 1rem; }

.theme-toggle {
  padding: var(--space-2); color: var(--color-text-muted);
  border-radius: var(--radius-sm); transition: all var(--transition-fast);
}
.theme-toggle:hover { color: var(--color-text); background: var(--color-surface-2); }

.global-progress {
  position: absolute; bottom: -2px; left: 0; right: 0;
  height: 2px; background: var(--color-border);
}
.global-progress-bar {
  height: 100%; background: linear-gradient(90deg, var(--color-accent), var(--color-accent-2), var(--color-accent-3));
  transition: width var(--transition-slow); border-radius: 0 2px 2px 0;
}

/* --- SIDEBAR --- */
.sidebar {
  position: fixed; top: var(--header-height); left: 0; bottom: 0;
  width: var(--sidebar-width); z-index: 90;
  background: var(--color-surface); border-right: 1px solid var(--color-border);
  overflow-y: auto; overflow-x: hidden;
  transition: transform var(--transition-med);
}
.sidebar-inner { padding: var(--space-4) 0; }
.sidebar-section { margin-bottom: var(--space-4); }
.sidebar-label {
  padding: var(--space-2) var(--space-4); font-size: var(--text-xs);
  font-weight: 600; letter-spacing: 0.08em; color: var(--color-text-faint);
  text-transform: uppercase;
}
.sidebar-link {
  display: flex; align-items: center; gap: var(--space-2);
  width: 100%; padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm); color: var(--color-text-muted);
  border: none; background: none; text-align: left;
  transition: all var(--transition-fast); border-left: 2px solid transparent;
}
.sidebar-link:hover { color: var(--color-text); background: var(--color-surface-2); }
.sidebar-link.active {
  color: var(--color-accent); background: var(--color-accent-dim);
  border-left-color: var(--color-accent); font-weight: 500;
}
.sidebar-link.completed .sidebar-icon { opacity: 0.6; }
.sidebar-icon { font-size: 1rem; flex-shrink: 0; width: 24px; text-align: center; }
.sidebar-text { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.track-progress-mini {
  font-size: var(--text-xs); color: var(--color-text-faint);
  font-variant-numeric: tabular-nums; min-width: 30px; text-align: right;
}
.sidebar-overlay {
  display: none; position: fixed; inset: 0; z-index: 85;
  background: rgba(0,0,0,0.5); backdrop-filter: blur(4px);
}

/* --- MAIN CONTENT --- */
.main-content {
  margin-left: var(--sidebar-width); margin-top: var(--header-height);
  min-height: calc(100dvh - var(--header-height));
  padding: var(--space-8) var(--space-6);
}
#content-area {
  max-width: var(--content-max); margin: 0 auto;
}

/* --- OVERVIEW PAGE --- */
.overview-hero {
  text-align: center; padding: var(--space-12) 0 var(--space-8);
}
.overview-hero h1 {
  font-size: var(--text-3xl); font-weight: 800; margin-bottom: var(--space-4);
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-2) 50%, var(--color-accent-3) 100%);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.overview-hero .subtitle {
  font-size: var(--text-lg); color: var(--color-text-muted);
  max-width: 640px; margin: 0 auto;
}
.overview-stats {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: var(--space-4); margin: var(--space-8) 0;
}
.stat-card {
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-lg); padding: var(--space-4); text-align: center;
}
.stat-value {
  font-size: var(--text-xl); font-weight: 700; font-variant-numeric: tabular-nums;
}
.stat-value.accent { color: var(--color-accent); }
.stat-value.accent2 { color: var(--color-accent-2); }
.stat-value.accent3 { color: var(--color-accent-3); }
.stat-value.xp-color { color: var(--color-xp); }
.stat-label { font-size: var(--text-sm); color: var(--color-text-muted); margin-top: var(--space-1); }

.track-cards {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-4); margin-top: var(--space-8);
}
.track-card {
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-lg); padding: var(--space-5);
  transition: all var(--transition-fast); cursor: pointer;
}
.track-card:hover { border-color: var(--color-accent); transform: translateY(-2px); box-shadow: var(--shadow-md); }
.track-card-header { display: flex; align-items: flex-start; gap: var(--space-3); margin-bottom: var(--space-3); }
.track-card-icon { font-size: 1.75rem; }
.track-card-title { font-size: var(--text-lg); font-weight: 600; }
.track-card-desc { font-size: var(--text-sm); color: var(--color-text-muted); margin-bottom: var(--space-4); }
.track-card-progress {
  height: 4px; background: var(--color-surface-3); border-radius: 2px; overflow: hidden;
}
.track-card-progress-bar {
  height: 100%; border-radius: 2px; transition: width var(--transition-med);
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-3));
}
.track-card-meta {
  display: flex; justify-content: space-between; align-items: center;
  margin-top: var(--space-2); font-size: var(--text-xs); color: var(--color-text-faint);
}

/* Level ladder */
.level-ladder {
  margin: var(--space-8) 0; background: var(--color-surface);
  border: 1px solid var(--color-border); border-radius: var(--radius-lg); padding: var(--space-6);
}
.level-ladder h2 { font-size: var(--text-xl); font-weight: 700; margin-bottom: var(--space-4); }
.level-list { display: flex; flex-direction: column; gap: var(--space-3); }
.level-item {
  display: flex; align-items: center; gap: var(--space-3);
  padding: var(--space-3) var(--space-4); border-radius: var(--radius-md);
  border: 1px solid var(--color-border); background: var(--color-bg);
  transition: all var(--transition-fast);
}
.level-item.current { border-color: var(--color-accent); background: var(--color-accent-dim); }
.level-item.unlocked { opacity: 1; }
.level-item.locked { opacity: 0.5; }
.level-item-icon { font-size: 1.5rem; width: 36px; text-align: center; }
.level-item-info { flex: 1; }
.level-item-name { font-weight: 600; font-size: var(--text-sm); }
.level-item-xp { font-size: var(--text-xs); color: var(--color-text-muted); font-variant-numeric: tabular-nums; }

/* --- TRACK PAGE --- */
.track-page { animation: fadeIn 0.3s ease; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }

.track-header {
  margin-bottom: var(--space-8); padding-bottom: var(--space-6);
  border-bottom: 1px solid var(--color-border);
}
.track-header-meta {
  display: flex; align-items: center; gap: var(--space-2);
  font-size: var(--text-sm); color: var(--color-text-muted); margin-bottom: var(--space-3);
}
.track-header h1 { font-size: var(--text-2xl); font-weight: 700; margin-bottom: var(--space-2); }
.track-header .track-desc { font-size: var(--text-base); color: var(--color-text-muted); max-width: 640px; }
.track-progress-bar-wrap {
  margin-top: var(--space-4); height: 6px; background: var(--color-surface-3);
  border-radius: 3px; overflow: hidden;
}
.track-progress-fill {
  height: 100%; border-radius: 3px; transition: width var(--transition-med);
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-3));
}
.track-progress-label {
  font-size: var(--text-xs); color: var(--color-text-muted); margin-top: var(--space-1);
  font-variant-numeric: tabular-nums;
}

/* --- LESSON SECTIONS --- */
.lesson-section {
  margin-bottom: var(--space-8); padding: var(--space-6);
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}
.lesson-section.completed { border-color: var(--color-accent-3); }
.lesson-section.completed .lesson-header::after {
  content: "✓"; color: var(--color-success); font-weight: 700; font-size: var(--text-lg);
}
.lesson-header {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: var(--space-4);
}
.lesson-header h2 {
  font-size: var(--text-lg); font-weight: 600;
  display: flex; align-items: center; gap: var(--space-2);
}
.lesson-number {
  font-size: var(--text-xs); font-weight: 600; color: var(--color-accent);
  background: var(--color-accent-dim); padding: 2px 8px;
  border-radius: var(--radius-full); font-variant-numeric: tabular-nums;
}
.lesson-content { font-size: var(--text-base); color: var(--color-text); }
.lesson-content p { margin-bottom: var(--space-4); max-width: 72ch; }
.lesson-content h3 {
  font-size: var(--text-base); font-weight: 600; margin-top: var(--space-6);
  margin-bottom: var(--space-3); color: var(--color-text);
}
.lesson-content h4 {
  font-size: var(--text-sm); font-weight: 600; margin-top: var(--space-4);
  margin-bottom: var(--space-2); color: var(--color-accent);
}
.lesson-content ul, .lesson-content ol {
  margin-bottom: var(--space-4); padding-left: var(--space-6);
}
.lesson-content li { margin-bottom: var(--space-2); }
.lesson-content strong { color: var(--color-text); font-weight: 600; }
.lesson-content em { color: var(--color-accent); font-style: normal; font-weight: 500; }

.complete-btn {
  display: inline-flex; align-items: center; gap: var(--space-2);
  margin-top: var(--space-4); padding: var(--space-2) var(--space-5);
  background: var(--color-accent); color: #000; font-weight: 600;
  font-size: var(--text-sm); border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}
.complete-btn:hover { filter: brightness(1.1); transform: translateY(-1px); }
.complete-btn.done { background: var(--color-surface-3); color: var(--color-text-muted); pointer-events: none; }
.complete-btn.done::before { content: "✓ "; }

/* --- CODE BLOCKS --- */
.code-block-wrap {
  position: relative; margin: var(--space-4) 0;
  border: 1px solid var(--code-border); border-radius: var(--radius-md);
  overflow: hidden;
}
.code-block-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: var(--space-2) var(--space-4);
  background: var(--code-bg); border-bottom: 1px solid var(--code-border);
  font-size: var(--text-xs); color: var(--color-text-faint);
}
.code-lang {
  font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em;
  color: var(--color-accent);
}
.copy-btn {
  display: flex; align-items: center; gap: var(--space-1);
  padding: 2px 8px; font-size: var(--text-xs); color: var(--color-text-faint);
  background: var(--color-surface-2); border: 1px solid var(--color-border);
  border-radius: var(--radius-sm); transition: all var(--transition-fast);
}
.copy-btn:hover { color: var(--color-text); border-color: var(--color-border-2); }
.copy-btn.copied { color: var(--color-success); border-color: var(--color-success); }
pre.code-block {
  margin: 0; padding: var(--space-4); background: var(--code-bg);
  overflow-x: auto; font-family: var(--font-code); font-size: var(--text-sm);
  line-height: 1.6; tab-size: 4; color: var(--color-text);
}
code { font-family: var(--font-code); }
.inline-code {
  font-family: var(--font-code); font-size: 0.9em;
  padding: 1px 6px; background: var(--color-surface-2);
  border: 1px solid var(--color-border); border-radius: 4px;
  color: var(--color-accent);
}

/* Syntax highlighting token classes */
.tok-kw { color: var(--code-keyword); font-weight: 500; }
.tok-str { color: var(--code-string); }
.tok-num { color: var(--code-number); }
.tok-cmt { color: var(--code-comment); font-style: italic; }
.tok-fn { color: var(--code-func); }
.tok-bi { color: var(--code-builtin); }
.tok-op { color: var(--code-operator); }
.tok-cls { color: var(--code-class); }
.tok-dec { color: var(--code-decorator); }
.tok-par { color: var(--code-param); }

/* --- CALLOUT BOXES --- */
.callout {
  padding: var(--space-4); margin: var(--space-4) 0;
  border-radius: var(--radius-md); border-left: 3px solid;
  font-size: var(--text-sm);
}
.callout-title {
  font-weight: 600; margin-bottom: var(--space-2); display: flex;
  align-items: center; gap: var(--space-2);
}
.callout.tip { background: var(--callout-tip-bg); border-color: var(--color-accent); }
.callout.tip .callout-title { color: var(--color-accent); }
.callout.warning { background: var(--callout-warn-bg); border-color: var(--color-warning); }
.callout.warning .callout-title { color: var(--color-warning); }
.callout.mistake { background: var(--callout-mistake-bg); border-color: var(--color-error); }
.callout.mistake .callout-title { color: var(--color-error); }
.callout.info { background: var(--callout-info-bg); border-color: var(--color-accent-2); }
.callout.info .callout-title { color: var(--color-accent-2); }

/* --- COMPARISON TABLES --- */
.data-table-wrap {
  margin: var(--space-4) 0; overflow-x: auto; border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}
.data-table {
  width: 100%; border-collapse: collapse; font-size: var(--text-sm);
  font-variant-numeric: tabular-nums;
}
.data-table th {
  text-align: left; padding: var(--space-3) var(--space-4);
  background: var(--color-surface-2); font-weight: 600;
  border-bottom: 1px solid var(--color-border); white-space: nowrap;
  font-size: var(--text-xs); text-transform: uppercase; letter-spacing: 0.04em;
  color: var(--color-text-muted);
}
.data-table td {
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--color-border);
}
.data-table tr:last-child td { border-bottom: none; }
.data-table tr:hover td { background: var(--color-surface-2); }

/* --- QUIZ SECTION --- */
.quiz-section {
  margin: var(--space-8) 0; padding: var(--space-6);
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}
.quiz-section h2 {
  font-size: var(--text-lg); font-weight: 700; margin-bottom: var(--space-4);
  display: flex; align-items: center; gap: var(--space-2);
}
.quiz-question {
  margin-bottom: var(--space-6); padding-bottom: var(--space-6);
  border-bottom: 1px solid var(--color-border);
}
.quiz-question:last-child { margin-bottom: 0; padding-bottom: 0; border: none; }
.quiz-q-text { font-weight: 500; margin-bottom: var(--space-3); }
.quiz-q-number { color: var(--color-accent); font-weight: 600; }
.quiz-options { display: flex; flex-direction: column; gap: var(--space-2); }
.quiz-option {
  display: flex; align-items: flex-start; gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  background: var(--color-bg); border: 1px solid var(--color-border);
  border-radius: var(--radius-md); cursor: pointer; font-size: var(--text-sm);
  transition: all var(--transition-fast); text-align: left; width: 100%;
}
.quiz-option:hover:not(.selected):not(.disabled) { border-color: var(--color-accent); background: var(--color-accent-dim); }
.quiz-option.selected.correct { border-color: var(--color-success); background: rgba(52, 211, 153, 0.1); }
.quiz-option.selected.wrong { border-color: var(--color-error); background: var(--color-error-dim); }
.quiz-option.disabled { cursor: default; opacity: 0.7; }
.quiz-option.show-correct { border-color: var(--color-success); background: rgba(52, 211, 153, 0.08); }
.quiz-option-letter {
  flex-shrink: 0; width: 24px; height: 24px;
  display: flex; align-items: center; justify-content: center;
  background: var(--color-surface-2); border-radius: var(--radius-full);
  font-size: var(--text-xs); font-weight: 600; color: var(--color-text-muted);
}
.quiz-option.selected.correct .quiz-option-letter { background: var(--color-success); color: #000; }
.quiz-option.selected.wrong .quiz-option-letter { background: var(--color-error); color: #fff; }
.quiz-explanation {
  margin-top: var(--space-3); padding: var(--space-3) var(--space-4);
  background: var(--callout-info-bg); border-radius: var(--radius-md);
  font-size: var(--text-sm); color: var(--color-text-muted); display: none;
  border: 1px solid var(--callout-info-border);
}
.quiz-explanation.visible { display: block; animation: fadeIn 0.3s ease; }

/* --- SEARCH MODAL --- */
.search-modal {
  position: fixed; inset: 0; z-index: 200; display: none;
  align-items: flex-start; justify-content: center; padding-top: 15vh;
}
.search-modal.open { display: flex; }
.search-backdrop {
  position: absolute; inset: 0; background: rgba(0,0,0,0.6);
  backdrop-filter: blur(6px);
}
.search-container {
  position: relative; width: 90%; max-width: 560px;
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--radius-lg); box-shadow: var(--shadow-lg);
  overflow: hidden; animation: slideDown 0.2s ease;
}
@keyframes slideDown { from { opacity: 0; transform: translateY(-16px); } to { opacity: 1; transform: translateY(0); } }
.search-input-wrap {
  display: flex; align-items: center; gap: var(--space-3);
  padding: var(--space-4); border-bottom: 1px solid var(--color-border);
  color: var(--color-text-muted);
}
.search-input-wrap input {
  flex: 1; background: none; border: none; font-size: var(--text-base);
  color: var(--color-text); outline: none;
}
.search-input-wrap kbd {
  padding: 2px 8px; font-size: var(--text-xs); background: var(--color-surface-2);
  border: 1px solid var(--color-border); border-radius: 4px;
  color: var(--color-text-faint); font-family: var(--font-body);
}
.search-results { max-height: 360px; overflow-y: auto; }
.search-result-item {
  display: flex; align-items: flex-start; gap: var(--space-3);
  padding: var(--space-3) var(--space-4); cursor: pointer;
  border-bottom: 1px solid var(--color-border);
  transition: background var(--transition-fast);
}
.search-result-item:hover { background: var(--color-surface-2); }
.search-result-track { font-size: var(--text-xs); color: var(--color-accent); font-weight: 500; }
.search-result-title { font-size: var(--text-sm); font-weight: 500; }
.search-result-snippet { font-size: var(--text-xs); color: var(--color-text-muted); margin-top: 2px; }
.search-empty {
  padding: var(--space-8); text-align: center;
  font-size: var(--text-sm); color: var(--color-text-muted);
}

/* --- LEVEL UP MODAL --- */
.levelup-modal {
  position: fixed; inset: 0; z-index: 300;
  display: none; align-items: center; justify-content: center;
  background: rgba(0,0,0,0.7); backdrop-filter: blur(8px);
}
.levelup-modal.open { display: flex; }
.levelup-content {
  text-align: center; padding: var(--space-10); background: var(--color-surface);
  border: 1px solid var(--color-accent); border-radius: var(--radius-xl);
  box-shadow: 0 0 60px rgba(34, 211, 197, 0.2); animation: popIn 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  max-width: 360px; width: 90%;
}
@keyframes popIn { from { opacity: 0; transform: scale(0.8); } to { opacity: 1; transform: scale(1); } }
.levelup-badge { font-size: 4rem; margin-bottom: var(--space-4); animation: bounce 0.6s ease infinite alternate; }
@keyframes bounce { from { transform: translateY(0); } to { transform: translateY(-8px); } }
.levelup-content h2 {
  font-size: var(--text-xl); font-weight: 700;
  background: linear-gradient(135deg, var(--color-accent), var(--color-xp));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
  margin-bottom: var(--space-2);
}
.levelup-content p { font-size: var(--text-sm); color: var(--color-text-muted); margin-bottom: var(--space-6); }
.btn-primary {
  display: inline-flex; padding: var(--space-3) var(--space-6);
  background: var(--color-accent); color: #000; font-weight: 600;
  border-radius: var(--radius-md); font-size: var(--text-sm);
  transition: all var(--transition-fast);
}
.btn-primary:hover { filter: brightness(1.1); transform: translateY(-1px); }

/* --- ACHIEVEMENT TOAST --- */
.achievement-toast {
  position: fixed; top: calc(var(--header-height) + var(--space-4)); right: var(--space-4);
  z-index: 250; display: flex; align-items: center; gap: var(--space-3);
  padding: var(--space-3) var(--space-5);
  background: var(--color-surface); border: 1px solid var(--color-xp);
  border-radius: var(--radius-lg); box-shadow: var(--shadow-lg);
  transform: translateX(120%); transition: transform var(--transition-med);
}
.achievement-toast.visible { transform: translateX(0); }
.toast-icon { font-size: 1.5rem; }
.toast-text { display: flex; flex-direction: column; }
.toast-text strong { font-size: var(--text-sm); color: var(--color-xp); }
.toast-text span { font-size: var(--text-xs); color: var(--color-text-muted); }

/* --- CONFETTI --- */
#confetti-canvas {
  position: fixed; inset: 0; z-index: 400; pointer-events: none;
}

/* --- ACHIEVEMENTS PAGE --- */
.achievements-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-4); margin-top: var(--space-6);
}
.achievement-card {
  padding: var(--space-5); background: var(--color-surface);
  border: 1px solid var(--color-border); border-radius: var(--radius-lg);
  text-align: center; transition: all var(--transition-fast);
}
.achievement-card.unlocked { border-color: var(--color-xp); }
.achievement-card.locked { opacity: 0.4; }
.achievement-icon { font-size: 2.5rem; margin-bottom: var(--space-2); }
.achievement-card.locked .achievement-icon { filter: grayscale(1); }
.achievement-name { font-weight: 600; font-size: var(--text-sm); margin-bottom: var(--space-1); }
.achievement-desc { font-size: var(--text-xs); color: var(--color-text-muted); }

/* --- MINI PROJECT SECTIONS --- */
.mini-project {
  margin: var(--space-4) 0; padding: var(--space-5);
  background: var(--color-purple-dim); border: 1px solid var(--color-purple);
  border-radius: var(--radius-md);
}
.mini-project-title {
  font-weight: 600; font-size: var(--text-sm); color: var(--color-purple);
  margin-bottom: var(--space-2); display: flex; align-items: center; gap: var(--space-2);
}

/* --- RESPONSIVE --- */
@media (max-width: 900px) {
  .sidebar { transform: translateX(-100%); z-index: 95; }
  .sidebar.open { transform: translateX(0); }
  .sidebar-overlay.open { display: block; }
  .main-content { margin-left: 0; }
  .menu-toggle { display: block; }
  .search-trigger { min-width: auto; }
  .search-trigger span { display: none; }
  .level-name { display: none; }
  .track-cards { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .main-content { padding: var(--space-4) var(--space-3); }
  .lesson-section { padding: var(--space-4); }
  .overview-hero { padding: var(--space-6) 0 var(--space-4); }
  .overview-stats { grid-template-columns: repeat(2, 1fr); }
  pre.code-block { font-size: var(--text-xs); padding: var(--space-3); }
  .quiz-section { padding: var(--space-4); }
}
@media (max-width: 380px) {
  .xp-display { display: none; }
  .header-center { display: none; }
}