@import url('https://fonts.googleapis.com/css2?family=Press+Start+2P&family=Orbitron:wght@400;700;900&family=Share+Tech+Mono&family=Exo+2:wght@300;400;600;800&display=swap');

:root {
  --bg-dark: #05050f;
  --bg-panel: #0d0d2b;
  --bg-card: #0a0a20;
  --accent-cyan: #00f5ff;
  --accent-magenta: #ff00aa;
  --accent-yellow: #ffe000;
  --accent-green: #00ff88;
  --accent-orange: #ff6600;
  --text-main: #e0e8ff;
  --text-dim: #7080a0;
  --border-glow: rgba(0,245,255,0.3);
  --grid-color: rgba(0,245,255,0.05);
  --scanline: rgba(0,0,0,0.3);
  --pixel-font: 'Press Start 2P', monospace;
  --title-font: 'Orbitron', sans-serif;
  --mono-font: 'Share Tech Mono', monospace;
  --body-font: 'Exo 2', sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg-dark);
  color: var(--text-main);
  font-family: var(--body-font);
  font-size: 16px;
  line-height: 1.7;
  overflow-x: hidden;
  background-image:
    linear-gradient(var(--grid-color) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-color) 1px, transparent 1px);
  background-size: 40px 40px;
  background-attachment: fixed;
}

/* Scanlines overlay */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background: repeating-linear-gradient(
    0deg,
    var(--scanline) 0px,
    var(--scanline) 1px,
    transparent 1px,
    transparent 3px
  );
  pointer-events: none;
  z-index: 9999;
  opacity: 0.15;
}

/* ─── NAV ─── */
#main-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  background: rgba(5,5,15,0.95);
  border-bottom: 2px solid var(--accent-cyan);
  box-shadow: 0 0 30px rgba(0,245,255,0.2);
  backdrop-filter: blur(10px);
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-logo {
  font-family: var(--pixel-font);
  font-size: 0.7rem;
  color: var(--accent-cyan);
  text-shadow: 0 0 10px var(--accent-cyan);
  text-decoration: none;
  letter-spacing: 2px;
  white-space: nowrap;
}
.nav-logo span { color: var(--accent-magenta); }

.nav-links {
  display: flex;
  gap: 0.2rem;
  list-style: none;
  align-items: center;
  flex-wrap: wrap;
}

.nav-links a {
  font-family: var(--mono-font);
  font-size: 0.75rem;
  color: var(--text-dim);
  text-decoration: none;
  padding: 0.4rem 0.8rem;
  border: 1px solid transparent;
  border-radius: 4px;
  transition: all 0.2s;
  letter-spacing: 1px;
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent-cyan);
  border-color: var(--accent-cyan);
  text-shadow: 0 0 8px var(--accent-cyan);
  background: rgba(0,245,255,0.05);
}

.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 5px;
  background: none;
  border: none;
}
.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--accent-cyan);
  transition: all 0.3s;
}

/* ─── HERO ─── */
#hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 6rem 2rem 4rem;
  position: relative;
  overflow: hidden;
}

.hero-bg-anim {
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 50% 50%, rgba(0,245,255,0.06) 0%, transparent 70%);
  animation: pulse-bg 4s ease-in-out infinite alternate;
}

@keyframes pulse-bg {
  from { opacity: 0.5; transform: scale(1); }
  to { opacity: 1; transform: scale(1.1); }
}

.hero-content { position: relative; z-index: 1; max-width: 800px; }

.hero-badge {
  display: inline-block;
  font-family: var(--pixel-font);
  font-size: 0.5rem;
  color: var(--accent-magenta);
  border: 1px solid var(--accent-magenta);
  padding: 0.4rem 1rem;
  margin-bottom: 2rem;
  letter-spacing: 3px;
  text-shadow: 0 0 10px var(--accent-magenta);
  box-shadow: 0 0 15px rgba(255,0,170,0.2);
  animation: blink-badge 2s step-end infinite;
}

@keyframes blink-badge {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.6; }
}

.hero-title {
  font-family: var(--title-font);
  font-size: clamp(2.5rem, 8vw, 5rem);
  font-weight: 900;
  line-height: 1.1;
  margin-bottom: 1rem;
}

.hero-title .line1 { color: var(--accent-cyan); text-shadow: 0 0 30px var(--accent-cyan), 0 0 60px rgba(0,245,255,0.4); }
.hero-title .line2 { color: var(--text-main); }
.hero-title .line3 { color: var(--accent-yellow); text-shadow: 0 0 20px var(--accent-yellow); }

.hero-sub {
  font-size: 1.1rem;
  color: var(--text-dim);
  margin: 1.5rem auto 2.5rem;
  max-width: 550px;
  font-weight: 300;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
  margin-bottom: 3rem;
}

.stat-item {
  text-align: center;
}
.stat-number {
  font-family: var(--title-font);
  font-size: 2rem;
  font-weight: 900;
  color: var(--accent-green);
  text-shadow: 0 0 15px var(--accent-green);
}
.stat-label {
  font-family: var(--mono-font);
  font-size: 0.7rem;
  color: var(--text-dim);
  letter-spacing: 2px;
  text-transform: uppercase;
}

.hero-cta {
  display: inline-flex;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
}

.btn-primary, .btn-secondary {
  font-family: var(--pixel-font);
  font-size: 0.55rem;
  padding: 1rem 2rem;
  text-decoration: none;
  letter-spacing: 2px;
  border-radius: 4px;
  transition: all 0.2s;
  display: inline-block;
}

.btn-primary {
  background: var(--accent-cyan);
  color: var(--bg-dark);
  border: 2px solid var(--accent-cyan);
  box-shadow: 0 0 20px rgba(0,245,255,0.4);
}
.btn-primary:hover {
  background: transparent;
  color: var(--accent-cyan);
  box-shadow: 0 0 30px rgba(0,245,255,0.6);
}

.btn-secondary {
  background: transparent;
  color: var(--accent-magenta);
  border: 2px solid var(--accent-magenta);
  box-shadow: 0 0 20px rgba(255,0,170,0.3);
}
.btn-secondary:hover {
  background: var(--accent-magenta);
  color: var(--bg-dark);
  box-shadow: 0 0 30px rgba(255,0,170,0.6);
}

/* ─── SECTION BASE ─── */
.section {
  padding: 5rem 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.section-header {
  text-align: center;
  margin-bottom: 4rem;
}

.section-label {
  font-family: var(--pixel-font);
  font-size: 0.5rem;
  color: var(--accent-magenta);
  letter-spacing: 4px;
  display: block;
  margin-bottom: 1rem;
}

.section-title {
  font-family: var(--title-font);
  font-size: clamp(1.8rem, 4vw, 3rem);
  font-weight: 900;
  color: var(--text-main);
  margin-bottom: 1rem;
}

.section-title span { color: var(--accent-cyan); }

.section-desc {
  color: var(--text-dim);
  max-width: 600px;
  margin: 0 auto;
  font-size: 1.05rem;
}

/* ─── CATEGORIES GRID ─── */
.categories-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.category-card {
  background: var(--bg-card);
  border: 1px solid rgba(0,245,255,0.15);
  border-radius: 8px;
  padding: 2rem;
  cursor: pointer;
  text-decoration: none;
  color: inherit;
  display: block;
  position: relative;
  overflow: hidden;
  transition: all 0.3s;
}

.category-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 3px;
  background: var(--card-accent, var(--accent-cyan));
  box-shadow: 0 0 20px var(--card-accent, var(--accent-cyan));
}

.category-card:hover {
  border-color: var(--card-accent, var(--accent-cyan));
  transform: translateY(-4px);
  box-shadow: 0 8px 40px rgba(0,245,255,0.1);
}

.card-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  display: block;
}

.card-number {
  font-family: var(--pixel-font);
  font-size: 0.4rem;
  color: var(--text-dim);
  letter-spacing: 3px;
  margin-bottom: 0.5rem;
}

.card-title {
  font-family: var(--title-font);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.75rem;
}

.card-desc {
  font-size: 0.9rem;
  color: var(--text-dim);
  line-height: 1.6;
}

.card-tag {
  display: inline-block;
  margin-top: 1rem;
  font-family: var(--mono-font);
  font-size: 0.75rem;
  color: var(--card-accent, var(--accent-cyan));
  border: 1px solid var(--card-accent, var(--accent-cyan));
  padding: 0.2rem 0.6rem;
  border-radius: 3px;
}

/* ─── LESSON PAGE ─── */
.lesson-layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 2rem;
  max-width: 1300px;
  margin: 0 auto;
  padding: 6rem 2rem 4rem;
  min-height: 100vh;
  align-items: start;
}

.lesson-sidebar {
  position: sticky;
  top: 80px;
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 8px;
  padding: 1.5rem;
  max-height: calc(100vh - 100px);
  overflow-y: auto;
}

.sidebar-title {
  font-family: var(--pixel-font);
  font-size: 0.5rem;
  color: var(--accent-cyan);
  letter-spacing: 2px;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-glow);
}

.sidebar-nav { list-style: none; }
.sidebar-nav li { margin-bottom: 0.5rem; }
.sidebar-nav a {
  font-family: var(--mono-font);
  font-size: 0.8rem;
  color: var(--text-dim);
  text-decoration: none;
  display: block;
  padding: 0.4rem 0.8rem;
  border-left: 2px solid transparent;
  transition: all 0.2s;
}
.sidebar-nav a:hover,
.sidebar-nav a.active {
  color: var(--accent-cyan);
  border-left-color: var(--accent-cyan);
  background: rgba(0,245,255,0.05);
}

.lesson-content { min-width: 0; }

.lesson-header {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border-glow);
}

.lesson-breadcrumb {
  font-family: var(--mono-font);
  font-size: 0.8rem;
  color: var(--text-dim);
  margin-bottom: 1rem;
}
.lesson-breadcrumb a { color: var(--accent-cyan); text-decoration: none; }
.lesson-breadcrumb a:hover { text-decoration: underline; }

.lesson-title {
  font-family: var(--title-font);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 900;
  color: var(--text-main);
  margin-bottom: 1rem;
  line-height: 1.2;
}

.lesson-meta {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.meta-badge {
  font-family: var(--mono-font);
  font-size: 0.75rem;
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  border: 1px solid;
}

.meta-badge.level-beginner { color: var(--accent-green); border-color: var(--accent-green); }
.meta-badge.level-intermediate { color: var(--accent-yellow); border-color: var(--accent-yellow); }
.meta-badge.level-advanced { color: var(--accent-orange); border-color: var(--accent-orange); }
.meta-badge.time { color: var(--accent-cyan); border-color: var(--accent-cyan); }

/* ─── CONTENT BLOCKS ─── */
.content-block { margin-bottom: 3rem; }

.block-title {
  font-family: var(--title-font);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent-cyan);
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.block-title::after {
  content: '';
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, var(--border-glow), transparent);
}

.content-text {
  color: var(--text-main);
  line-height: 1.8;
  margin-bottom: 1rem;
  font-size: 1rem;
}

.content-text strong { color: var(--accent-cyan); font-weight: 600; }

/* ─── CODE BLOCKS ─── */
.code-container {
  position: relative;
  margin: 1.5rem 0;
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid rgba(0,245,255,0.2);
}

.code-header {
  background: rgba(0,245,255,0.08);
  padding: 0.6rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid rgba(0,245,255,0.1);
}

.code-lang {
  font-family: var(--mono-font);
  font-size: 0.75rem;
  color: var(--accent-cyan);
  letter-spacing: 1px;
}

.code-dots {
  display: flex;
  gap: 6px;
}
.code-dots span {
  width: 10px; height: 10px;
  border-radius: 50%;
}
.code-dots span:nth-child(1) { background: #ff5f56; }
.code-dots span:nth-child(2) { background: #ffbd2e; }
.code-dots span:nth-child(3) { background: #27c93f; }

.copy-btn {
  font-family: var(--mono-font);
  font-size: 0.7rem;
  color: var(--text-dim);
  background: none;
  border: 1px solid var(--text-dim);
  padding: 0.2rem 0.6rem;
  border-radius: 3px;
  cursor: pointer;
  transition: all 0.2s;
}
.copy-btn:hover {
  color: var(--accent-cyan);
  border-color: var(--accent-cyan);
}

pre {
  background: var(--bg-panel);
  padding: 1.5rem;
  overflow-x: auto;
  margin: 0;
}

code {
  font-family: var(--mono-font);
  font-size: 0.9rem;
  line-height: 1.8;
}

/* Syntax highlight */
.kw { color: #ff79c6; }
.fn { color: #50fa7b; }
.st { color: #f1fa8c; }
.cm { color: #6272a4; font-style: italic; }
.nm { color: #bd93f9; }
.cl { color: #8be9fd; }
.op { color: #ff79c6; }
.nb { color: #ffb86c; }

/* ─── CALLOUTS ─── */
.callout {
  border-radius: 8px;
  padding: 1.25rem 1.5rem;
  margin: 1.5rem 0;
  display: flex;
  gap: 1rem;
  align-items: flex-start;
  border: 1px solid;
}

.callout-icon { font-size: 1.3rem; flex-shrink: 0; margin-top: 0.1rem; }
.callout-text { font-size: 0.95rem; line-height: 1.7; }

.callout.info {
  background: rgba(0,245,255,0.06);
  border-color: rgba(0,245,255,0.3);
  color: #a0d8ef;
}
.callout.warning {
  background: rgba(255,224,0,0.06);
  border-color: rgba(255,224,0,0.3);
  color: #f0d88a;
}
.callout.success {
  background: rgba(0,255,136,0.06);
  border-color: rgba(0,255,136,0.3);
  color: #90f0c0;
}
.callout.danger {
  background: rgba(255,0,100,0.06);
  border-color: rgba(255,0,100,0.3);
  color: #f09090;
}

/* ─── VISUALIZATION ─── */
.viz-container {
  background: var(--bg-panel);
  border: 1px solid var(--border-glow);
  border-radius: 8px;
  padding: 1.5rem;
  margin: 2rem 0;
}

.viz-title {
  font-family: var(--mono-font);
  font-size: 0.8rem;
  color: var(--accent-magenta);
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 1rem;
}

canvas.viz-canvas {
  width: 100%;
  max-width: 700px;
  border-radius: 4px;
  display: block;
  margin: 0 auto;
  border: 1px solid rgba(0,245,255,0.1);
}

/* ─── QUIZ ─── */
.quiz-container {
  background: var(--bg-panel);
  border: 2px solid var(--accent-magenta);
  border-radius: 12px;
  padding: 2rem;
  margin: 3rem 0;
  box-shadow: 0 0 40px rgba(255,0,170,0.1);
  position: relative;
  overflow: hidden;
}

.quiz-container::before {
  content: '🎮 QUIZ TIME';
  position: absolute;
  top: -1px; left: 50%;
  transform: translateX(-50%);
  font-family: var(--pixel-font);
  font-size: 0.45rem;
  background: var(--accent-magenta);
  color: var(--bg-dark);
  padding: 0.3rem 1rem;
  letter-spacing: 2px;
  border-radius: 0 0 6px 6px;
}

.quiz-progress {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 2rem;
  margin-top: 1rem;
}

.quiz-dot {
  width: 12px; height: 12px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 2px solid var(--text-dim);
  transition: all 0.3s;
}
.quiz-dot.done { background: var(--accent-green); border-color: var(--accent-green); }
.quiz-dot.current { background: var(--accent-magenta); border-color: var(--accent-magenta); box-shadow: 0 0 8px var(--accent-magenta); }

.quiz-question {
  font-family: var(--title-font);
  font-size: 1.1rem;
  color: var(--text-main);
  margin-bottom: 1.5rem;
  font-weight: 600;
}

.quiz-question-num {
  font-family: var(--pixel-font);
  font-size: 0.45rem;
  color: var(--accent-magenta);
  display: block;
  margin-bottom: 0.5rem;
}

.quiz-options {
  display: grid;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.quiz-option {
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 8px;
  padding: 1rem 1.25rem;
  cursor: pointer;
  font-family: var(--mono-font);
  font-size: 0.9rem;
  color: var(--text-main);
  text-align: left;
  transition: all 0.2s;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.quiz-option:hover:not(:disabled) {
  border-color: var(--accent-cyan);
  background: rgba(0,245,255,0.05);
  transform: translateX(4px);
}

.quiz-option.correct {
  border-color: var(--accent-green);
  background: rgba(0,255,136,0.1);
  color: var(--accent-green);
}

.quiz-option.wrong {
  border-color: #ff4444;
  background: rgba(255,68,68,0.1);
  color: #ff8888;
}

.option-letter {
  width: 28px; height: 28px;
  border-radius: 50%;
  background: rgba(255,255,255,0.08);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 700;
  flex-shrink: 0;
}

.quiz-feedback {
  padding: 1rem;
  border-radius: 6px;
  font-family: var(--mono-font);
  font-size: 0.9rem;
  display: none;
  margin-bottom: 1rem;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn { from { opacity: 0; transform: translateY(-5px); } to { opacity: 1; transform: translateY(0); } }

.quiz-feedback.show { display: block; }
.quiz-feedback.correct { background: rgba(0,255,136,0.1); color: var(--accent-green); border: 1px solid var(--accent-green); }
.quiz-feedback.wrong { background: rgba(255,68,68,0.1); color: #ff8888; border: 1px solid #ff4444; }

.quiz-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.btn-quiz {
  font-family: var(--pixel-font);
  font-size: 0.5rem;
  padding: 0.8rem 1.5rem;
  border-radius: 4px;
  cursor: pointer;
  letter-spacing: 1px;
  border: 2px solid;
  transition: all 0.2s;
  background: none;
}

.btn-quiz.next {
  color: var(--accent-cyan);
  border-color: var(--accent-cyan);
}
.btn-quiz.next:hover {
  background: var(--accent-cyan);
  color: var(--bg-dark);
}

.btn-quiz.restart {
  color: var(--accent-magenta);
  border-color: var(--accent-magenta);
}
.btn-quiz.restart:hover {
  background: var(--accent-magenta);
  color: var(--bg-dark);
}

.quiz-score {
  font-family: var(--title-font);
  font-size: 1rem;
  color: var(--text-dim);
}
.quiz-score span { color: var(--accent-green); }

/* ─── RESULT SCREEN ─── */
.quiz-result {
  text-align: center;
  padding: 2rem;
}

.result-score-big {
  font-family: var(--pixel-font);
  font-size: 2rem;
  color: var(--accent-yellow);
  text-shadow: 0 0 20px var(--accent-yellow);
  margin: 1rem 0;
}

.result-title {
  font-family: var(--title-font);
  font-size: 1.5rem;
  color: var(--text-main);
  margin-bottom: 0.5rem;
}

.result-message {
  color: var(--text-dim);
  font-size: 0.95rem;
  margin-bottom: 2rem;
}

.result-stars {
  font-size: 2rem;
  letter-spacing: 0.5rem;
  margin-bottom: 1.5rem;
}

/* ─── PROGRESS BAR ─── */
.progress-bar-wrap {
  background: rgba(255,255,255,0.05);
  border-radius: 100px;
  height: 8px;
  margin-bottom: 2rem;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  border-radius: 100px;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-magenta));
  transition: width 0.5s ease;
  box-shadow: 0 0 10px var(--accent-cyan);
}

/* ─── FEATURE BOXES ─── */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}

.feature-box {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 6px;
  padding: 1.25rem;
}

.feature-box h4 {
  font-family: var(--title-font);
  font-size: 0.9rem;
  color: var(--accent-cyan);
  margin-bottom: 0.5rem;
}

.feature-box p {
  font-size: 0.85rem;
  color: var(--text-dim);
  line-height: 1.6;
}

/* ─── TABLE ─── */
.styled-table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-family: var(--mono-font);
  font-size: 0.85rem;
}

.styled-table thead {
  background: rgba(0,245,255,0.1);
}

.styled-table th {
  padding: 0.75rem 1rem;
  text-align: left;
  color: var(--accent-cyan);
  font-weight: 700;
  letter-spacing: 1px;
  border-bottom: 2px solid var(--accent-cyan);
}

.styled-table td {
  padding: 0.65rem 1rem;
  border-bottom: 1px solid rgba(255,255,255,0.05);
  color: var(--text-main);
}

.styled-table tr:hover td {
  background: rgba(0,245,255,0.03);
}

/* ─── TABS ─── */
.tabs-container { margin: 1.5rem 0; }

.tab-buttons {
  display: flex;
  gap: 0;
  border-bottom: 2px solid var(--border-glow);
  flex-wrap: wrap;
}

.tab-btn {
  font-family: var(--mono-font);
  font-size: 0.8rem;
  color: var(--text-dim);
  background: none;
  border: none;
  padding: 0.75rem 1.25rem;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: all 0.2s;
  letter-spacing: 1px;
  white-space: nowrap;
}

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

.tab-panel { display: none; padding: 1.5rem 0; }
.tab-panel.active { display: block; }

/* ─── STEP LIST ─── */
.step-list { counter-reset: steps; list-style: none; }

.step-item {
  counter-increment: steps;
  display: flex;
  gap: 1.5rem;
  margin-bottom: 2rem;
  position: relative;
}

.step-item::before {
  content: counter(steps);
  width: 40px; height: 40px;
  border-radius: 50%;
  background: rgba(0,245,255,0.1);
  border: 2px solid var(--accent-cyan);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--pixel-font);
  font-size: 0.5rem;
  color: var(--accent-cyan);
  flex-shrink: 0;
  z-index: 1;
}

.step-item::after {
  content: '';
  position: absolute;
  left: 19px;
  top: 40px;
  bottom: -2rem;
  width: 2px;
  background: linear-gradient(var(--border-glow), transparent);
}

.step-item:last-child::after { display: none; }

.step-body { padding-top: 0.5rem; }
.step-title {
  font-family: var(--title-font);
  font-size: 1rem;
  color: var(--text-main);
  margin-bottom: 0.5rem;
}
.step-desc { font-size: 0.9rem; color: var(--text-dim); }

/* ─── NEXT/PREV LESSON ─── */
.lesson-footer {
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-glow);
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.lesson-nav-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 8px;
  padding: 1rem 1.5rem;
  text-decoration: none;
  color: var(--text-dim);
  transition: all 0.3s;
  max-width: 250px;
  flex: 1;
}

.lesson-nav-btn:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
}

.nav-direction {
  font-family: var(--pixel-font);
  font-size: 0.4rem;
  letter-spacing: 2px;
  display: block;
  margin-bottom: 0.5rem;
}

.nav-title {
  font-family: var(--title-font);
  font-size: 0.9rem;
  font-weight: 600;
}

/* ─── FOOTER ─── */
#main-footer {
  background: var(--bg-panel);
  border-top: 2px solid var(--border-glow);
  padding: 3rem 2rem;
  text-align: center;
  margin-top: 4rem;
}

.footer-logo {
  font-family: var(--pixel-font);
  font-size: 0.6rem;
  color: var(--accent-cyan);
  text-shadow: 0 0 10px var(--accent-cyan);
  letter-spacing: 3px;
  margin-bottom: 1rem;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
  list-style: none;
}

.footer-links a {
  font-family: var(--mono-font);
  font-size: 0.8rem;
  color: var(--text-dim);
  text-decoration: none;
  transition: color 0.2s;
}
.footer-links a:hover { color: var(--accent-cyan); }

.footer-copy {
  font-family: var(--mono-font);
  font-size: 0.75rem;
  color: var(--text-dim);
}

/* ─── PARTICLE CANVAS ─── */
#particle-canvas {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  pointer-events: none;
  z-index: 0;
  opacity: 0.4;
}

/* ─── HOME WRAPPER ─── */
#home-content {
  position: relative;
  z-index: 1;
}

/* ─── MOBILE ─── */
@media (max-width: 768px) {
  .hamburger { display: flex; }

  .nav-links {
    display: none;
    position: fixed;
    top: 64px; left: 0; right: 0;
    background: rgba(5,5,15,0.98);
    flex-direction: column;
    padding: 1rem;
    border-bottom: 1px solid var(--border-glow);
    z-index: 999;
    gap: 0.5rem;
  }

  .nav-links.open { display: flex; }
  .nav-links a { padding: 0.75rem 1rem; border-bottom: 1px solid rgba(255,255,255,0.05); }

  .lesson-layout {
    grid-template-columns: 1fr;
    padding: 5rem 1rem 3rem;
  }

  .lesson-sidebar {
    position: static;
    max-height: none;
    display: none;
  }

  .lesson-sidebar.open { display: block; }

  .mobile-toc-btn {
    display: block;
    font-family: var(--mono-font);
    font-size: 0.8rem;
    color: var(--accent-cyan);
    background: var(--bg-card);
    border: 1px solid var(--border-glow);
    padding: 0.6rem 1rem;
    border-radius: 6px;
    cursor: pointer;
    margin-bottom: 1.5rem;
    width: 100%;
    text-align: left;
  }

  .categories-grid {
    grid-template-columns: 1fr;
  }

  .hero-stats { gap: 1.5rem; }
  .stat-number { font-size: 1.5rem; }

  .lesson-footer { flex-direction: column; }
  .lesson-nav-btn { max-width: 100%; }

  .tab-btn { font-size: 0.7rem; padding: 0.6rem 0.8rem; }

  .styled-table { font-size: 0.75rem; }
  .styled-table th, .styled-table td { padding: 0.5rem 0.6rem; }
}

@media (max-width: 480px) {
  .nav-logo { font-size: 0.55rem; }
  .hero-title { font-size: 2rem; }
  .btn-primary, .btn-secondary { font-size: 0.45rem; padding: 0.8rem 1.2rem; }
  .result-score-big { font-size: 1.2rem; }
  pre { font-size: 0.75rem; }
}

/* ─── SCROLL ─── */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg-dark); }
::-webkit-scrollbar-thumb { background: rgba(0,245,255,0.3); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent-cyan); }

/* ─── ANIMATIONS ─── */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  animation: fadeInUp 0.6s ease forwards;
}

@keyframes fadeInUp {
  to { opacity: 1; transform: translateY(0); }
}

.glow-text { animation: glow-pulse 2s ease-in-out infinite alternate; }
@keyframes glow-pulse {
  from { text-shadow: 0 0 10px currentColor; }
  to { text-shadow: 0 0 25px currentColor, 0 0 50px currentColor; }
}

/* Mobile toc button hidden on desktop */
.mobile-toc-btn { display: none; }

/* API Quick Ref */
.api-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}

.api-item {
  background: var(--bg-card);
  border: 1px solid rgba(0,245,255,0.1);
  border-radius: 6px;
  padding: 1rem;
  transition: all 0.2s;
}

.api-item:hover {
  border-color: var(--accent-cyan);
  transform: translateY(-2px);
}

.api-name {
  font-family: var(--mono-font);
  font-size: 0.85rem;
  color: var(--accent-green);
  margin-bottom: 0.4rem;
  word-break: break-all;
}

.api-desc {
  font-size: 0.8rem;
  color: var(--text-dim);
  line-height: 1.5;
}

/* Tooltip */
.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: 1px dashed var(--accent-cyan);
  cursor: help;
}

.tooltip::after {
  content: attr(data-tip);
  position: absolute;
  bottom: 130%;
  left: 50%;
  transform: translateX(-50%);
  background: var(--bg-panel);
  border: 1px solid var(--accent-cyan);
  color: var(--text-main);
  padding: 0.5rem 0.75rem;
  border-radius: 4px;
  font-size: 0.8rem;
  white-space: nowrap;
  font-family: var(--mono-font);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s;
  z-index: 100;
}

.tooltip:hover::after { opacity: 1; }