/* ===========================
   AI BUILDER LAB - PREMIUM CSS DESIGN SYSTEM
   Dark theme with electric indigo accents for premium teen AI education
   =========================== */

/* ROOT VARIABLES */
:root {
  /* Color Palette - Deep, Rich, Premium */
  --bg-primary: #0a0a1a;
  --bg-secondary: #12122a;
  --bg-tertiary: #1a1a35;
  --surface: #0f0f24;
  --surface2: #16162e;
  --surface3: #1d1d3a;
  --bg: #0a0a1a;

  /* Accent Gradient - Electric Indigo to Sky Blue */
  --accent: #7c5cfc;
  --accent-light: #9d7eff;
  --accent-bright: #a78bfa;
  --accent-dim: #5b8def;
  --accent-gradient: linear-gradient(135deg, #7c5cfc 0%, #5b8def 100%);

  /* Secondary Colors */
  --cyan: #22d3ee;
  --green: #10b981;
  --orange: #f97066;
  --pink: #ec4899;

  /* Warm & Cool Variants */
  --amber: #f59e0b;
  --emerald: #10b981;
  --coral: #f97066;

  /* Text Colors */
  --text: #f0f0f5;
  --text-muted: #c4c4d8;
  --text-dim: #8b8ba3;

  /* Borders & Dividers */
  --border: rgba(124, 92, 252, 0.1);
  --border-bright: rgba(124, 92, 252, 0.25);

  /* Typography */
  --font-display: 'Instrument Serif', serif;
  --font-body: 'Outfit', sans-serif;

  /* Spacing Scale */
  --spacing-xs: 8px;
  --spacing-sm: 12px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;
  --spacing-3xl: 64px;

  /* Radius */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;

  /* Shadows */
  --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);

  /* Transitions */
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
}

body {
  background: var(--bg-primary);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  letter-spacing: 0.3px;
  -webkit-font-smoothing: antialiased;
}

/* TYPOGRAPHY */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  line-height: 1.2;
  letter-spacing: -0.5px;
}

h1 {
  font-size: clamp(2.2rem, 5vw, 4.5rem);
  font-weight: 600;
  margin-bottom: var(--spacing-2xl);
}

h2 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 600;
  margin-bottom: var(--spacing-xl);
}

h3 {
  font-size: clamp(1.3rem, 3vw, 1.5rem);
  font-weight: 600;
  margin-bottom: var(--spacing-lg);
}

h4 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
}

h5, h6 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
}

p {
  font-size: 17px;
  line-height: 1.75;
  margin-bottom: var(--spacing-lg);
  color: var(--text-muted);
}

strong {
  color: var(--text);
  font-weight: 600;
}

a {
  color: var(--accent-bright);
  text-decoration: none;
  transition: color 0.3s ease;
}

a:hover {
  color: var(--cyan);
}

ul {
  list-style: none;
}

button {
  font-family: var(--font-body);
  cursor: pointer;
}

img {
  max-width: 100%;
}

/* ACCENT TEXT */
.accent-italic {
  font-style: italic;
  color: var(--accent-bright);
}

/* CONTAINER */
.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

/* BUTTONS */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  font-size: 0.95rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
  white-space: nowrap;
}

.btn:active {
  transform: translateY(2px);
}

.btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.btn-primary {
  background: var(--accent-gradient);
  color: #fff;
  box-shadow: 0 12px 40px rgba(124, 92, 252, 0.25);
}

.btn-primary:hover {
  box-shadow: 0 16px 50px rgba(124, 92, 252, 0.35);
  transform: translateY(-2px);
}

.btn-secondary {
  background: transparent;
  color: var(--accent-bright);
  border: 2px solid var(--border-bright);
}

.btn-secondary:hover {
  background: rgba(124, 92, 252, 0.1);
  border-color: var(--accent-bright);
}

.btn:disabled,
.btn[disabled] {
  opacity: 0.4;
  cursor: not-allowed;
  pointer-events: none;
}

.btn-lg {
  padding: 18px 48px;
  font-size: 1.05rem;
  border-radius: 14px;
}

.btn-sm {
  padding: 10px 20px;
  font-size: 0.85rem;
}

/* ===========================
   NAVBAR
   =========================== */

.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 10, 26, 0.8);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: var(--spacing-md) 0;
  transition: var(--transition);
}

.navbar.scrolled {
  background: rgba(10, 10, 26, 0.9);
  border-bottom: 1px solid var(--border);
}

.navbar-container, .navbar-content {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.navbar-logo, .logo {
  font-family: var(--font-display);
  font-size: 1.4rem;
  color: var(--text);
  text-decoration: none;
}

.navbar-logo a, .logo a {
  font-family: var(--font-display);
  font-size: 1.4rem;
  color: var(--text);
  text-decoration: none;
}

.logo-accent, .accent-italic {
  color: var(--accent);
  font-style: italic;
}

.navbar-menu, .nav-links, .navbar-links {
  display: flex;
  gap: var(--spacing-2xl);
  list-style: none;
  align-items: center;
}

.navbar-menu a, .nav-link {
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.3s ease;
  text-decoration: none;
}

.navbar-menu a:hover, .nav-link:hover {
  color: var(--text);
}

.navbar-cta {
  background: linear-gradient(135deg, var(--accent), var(--accent-secondary));
  color: #fff;
  padding: 8px 20px;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.9rem;
  text-decoration: none;
  transition: all 0.3s ease;
  white-space: nowrap;
}

.navbar-cta:hover {
  box-shadow: 0 4px 15px rgba(124, 92, 252, 0.4);
  transform: translateY(-1px);
  color: #fff;
}

.nav-active {
  color: var(--accent-bright) !important;
  position: relative;
}

.nav-active::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent-gradient);
  border-radius: 1px;
}

/* ===========================
   HERO SECTION
   =========================== */

.hero {
  position: relative;
  overflow: hidden;
  padding: 120px 0 100px;
  background: var(--bg-primary);
}

/* Animated Gradient Mesh Background */
.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(124, 92, 252, 0.15) 0%, transparent 70%);
  border-radius: 50%;
  animation: float 8s ease-in-out infinite;
}

.hero::after {
  content: '';
  position: absolute;
  top: 20%;
  left: -15%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(34, 211, 238, 0.1) 0%, transparent 70%);
  border-radius: 50%;
  animation: float 10s ease-in-out infinite reverse;
}

@keyframes float {
  0%, 100% { transform: translateY(0px); }
  50% { transform: translateY(30px); }
}

.hero-glow {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(123, 92, 252, 0.08) 0%, transparent 70%);
  border-radius: 50%;
  filter: blur(80px);
}

.hero-content {
  position: relative;
  z-index: 1;
  text-align: center;
}

.label-pill {
  display: inline-block;
  background: rgba(124, 92, 252, 0.15);
  color: var(--accent-bright);
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.5px;
  text-transform: uppercase;
  margin-bottom: var(--spacing-lg);
  border: 1px solid var(--border);
}

.hero-title {
  background: linear-gradient(135deg, #f0f0f5 0%, var(--accent-bright) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--spacing-lg);
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto var(--spacing-2xl);
  line-height: 1.8;
}

.hero-buttons {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: var(--spacing-3xl);
}

.hero-stats {
  display: flex;
  gap: var(--spacing-3xl);
  justify-content: center;
  flex-wrap: wrap;
  margin-top: var(--spacing-2xl);
}

.stat {
  text-align: center;
}

.stat-number {
  font-family: var(--font-display);
  font-size: 2.5rem;
  color: var(--accent-bright);
  font-weight: 700;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-dim);
  margin-top: var(--spacing-sm);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* ===========================
   SECTION BLOCKS
   =========================== */

.tracks, .why-different {
  background: var(--surface);
  padding: 80px 0;
  position: relative;
}

.section-header {
  margin-bottom: var(--spacing-2xl);
  text-align: center;
}

.section-label {
  display: inline-block;
  color: var(--accent-bright);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  margin-bottom: var(--spacing-md);
}

.section-title {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-lg);
}

.section-subtitle {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.8;
}

/* ===========================
   TRACKS GRID
   =========================== */

.tracks-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.track-card {
  position: relative;
  background: rgba(22, 22, 46, 0.6);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: var(--spacing-2xl);
  overflow: hidden;
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
}

.track-card:hover {
  transform: translateY(-8px);
  border-color: var(--border-bright);
  background: rgba(26, 26, 53, 0.8);
  box-shadow: 0 20px 60px rgba(124, 92, 252, 0.15);
}

.track-top-border {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
}

.track-green { background: var(--emerald); }
.track-indigo { background: var(--accent-gradient); }
.track-orange { background: var(--coral); }

.track-icon {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-md);
  display: inline-block;
}

.track-title {
  font-size: 1.3rem;
  font-weight: 700;
  font-family: var(--font-body);
  margin-bottom: var(--spacing-md);
}

.track-description {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: var(--spacing-lg);
  line-height: 1.6;
}

.track-examples {
  font-size: 0.85rem;
  color: var(--text-dim);
}

.example-label {
  font-weight: 700;
  color: var(--text-muted);
  margin-bottom: var(--spacing-sm);
  text-transform: uppercase;
  letter-spacing: 0.4px;
  font-size: 0.75rem;
}

/* ===========================
   CURRICULUM SECTION
   =========================== */

.curriculum-list {
  max-width: 720px;
}

.curriculum-item {
  display: flex;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-2xl);
  padding-bottom: var(--spacing-2xl);
  border-bottom: 1px solid var(--border);
}

.curriculum-number {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 50px;
  height: 50px;
  background: var(--accent-gradient);
  border-radius: 12px;
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 700;
  color: #fff;
}

.curriculum-description {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 0;
}

/* ===========================
   WHY DIFFERENT SECTION
   =========================== */

.why-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-2xl);
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.why-card {
  background: rgba(22, 22, 46, 0.5);
  padding: var(--spacing-2xl);
  border-radius: 16px;
  border: 1px solid var(--border);
  transition: all 0.3s ease;
}

.why-card:hover {
  border-color: var(--border-bright);
  background: rgba(26, 26, 53, 0.7);
}

.why-icon {
  font-size: 2rem;
  margin-bottom: var(--spacing-md);
}

.why-title {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: var(--spacing-md);
  font-family: var(--font-body);
}

.why-description {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 0;
  line-height: 1.7;
}

/* ===========================
   FAQ SECTION
   =========================== */

.faq-list {
  max-width: 720px;
}

.faq-item {
  border-bottom: 1px solid var(--border);
  padding: var(--spacing-lg) 0;
}

.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  background: none;
  border: none;
  padding: 0;
  text-align: left;
  cursor: pointer;
  user-select: none;
  transition: color 0.3s ease;
  font-family: var(--font-body);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
}

.faq-question:hover {
  color: var(--accent-bright);
}

.faq-icon {
  font-size: 1.2rem;
  color: var(--accent);
  transition: transform 0.3s ease;
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
}

.faq-answer {
  display: none;
  margin-top: var(--spacing-lg);
  color: var(--text-muted);
  line-height: 1.8;
}

.faq-item.active .faq-answer {
  display: block;
  animation: slideDown 0.3s ease-out;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===========================
   PRICING SECTION
   =========================== */

.pricing {
  text-align: center;
  padding: 80px 0;
  background: var(--surface);
}

.pricing-card {
  display: inline-block;
  background: linear-gradient(135deg, rgba(22, 22, 46, 0.8) 0%, rgba(26, 26, 53, 0.6) 100%);
  backdrop-filter: blur(20px);
  border: 1.5px solid var(--border-bright);
  border-radius: 20px;
  padding: var(--spacing-3xl);
  max-width: 420px;
  position: relative;
  box-shadow: 0 25px 80px rgba(124, 92, 252, 0.1);
  transition: all 0.4s ease;
}

.pricing-card:hover {
  transform: translateY(-12px);
  box-shadow: 0 35px 100px rgba(124, 92, 252, 0.2);
  border-color: var(--accent-bright);
}

.pricing-card::before {
  content: '';
  position: absolute;
  top: -2px;
  left: 20%;
  right: 20%;
  height: 1px;
  background: var(--accent-gradient);
  opacity: 0;
  transition: opacity 0.4s ease;
}

.pricing-card:hover::before {
  opacity: 1;
}

.price-badge {
  display: inline-block;
  background: var(--accent-gradient);
  color: #fff;
  padding: 12px 24px;
  border-radius: 10px;
  font-family: var(--font-display);
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: var(--spacing-md);
}

.price-label {
  color: var(--text-muted);
  font-size: 1rem;
  margin-bottom: var(--spacing-2xl);
}

.price-subtext {
  margin-top: var(--spacing-lg);
  font-size: 0.85rem;
  color: var(--text-dim);
}

.price-features {
  text-align: left;
  margin: var(--spacing-2xl) 0;
}

.feature-group {
  margin-bottom: var(--spacing-lg);
}

.feature-group-title {
  font-size: 0.75rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.6px;
  margin-bottom: var(--spacing-md);
  font-weight: 700;
}

.feature-list {
  padding: 0;
  list-style: none;
}

.feature-list li {
  padding: 10px 0;
  color: var(--text-muted);
  font-size: 0.95rem;
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.feature-list li::before {
  content: '✓';
  color: var(--emerald);
  font-weight: 700;
  font-size: 1.1rem;
}

/* ===========================
   FINAL CTA SECTION
   =========================== */

.final-cta {
  text-align: center;
  padding: 120px 0;
  position: relative;
  background: var(--bg-primary);
}

.cta-glow {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 700px;
  height: 700px;
  background: radial-gradient(circle, rgba(124, 92, 252, 0.1) 0%, transparent 70%);
  border-radius: 50%;
  filter: blur(100px);
}

.cta-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
}

.cta-title {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  margin-bottom: var(--spacing-lg);
}

.cta-subtitle {
  color: var(--text-muted);
  font-size: 1.1rem;
  margin-bottom: var(--spacing-2xl);
  line-height: 1.8;
}

/* ===========================
   DASHBOARD & MODULE CARDS
   =========================== */

.page-header {
  background: var(--surface);
  padding: 40px 0;
  border-bottom: 1px solid var(--border);
}

.header-container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.dashboard-main {
  padding: 40px 0 80px;
}

.modules-section {
  margin-bottom: 60px;
}

.module-card {
  background: rgba(22, 22, 46, 0.6);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
}

.module-card:hover {
  border-color: var(--border-bright);
  background: rgba(26, 26, 53, 0.8);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.3);
  transform: translateY(-4px);
}

.color-indigo { border-left: 5px solid var(--accent); }
.color-green { border-left: 5px solid var(--emerald); }
.color-orange { border-left: 5px solid var(--coral); }
.color-pink { border-left: 5px solid var(--pink); }

.module-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  user-select: none;
}

.module-header-left {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  flex: 1;
  min-width: 0;
}

.module-number {
  flex-shrink: 0;
  width: 45px;
  height: 45px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-gradient);
  border-radius: 10px;
  font-weight: 700;
  font-size: 1.1rem;
  color: #fff;
}

.module-title-group {
  flex: 1;
  min-width: 0;
}

.module-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 4px;
}

.badge {
  display: inline-block;
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.4px;
}

.badge-free {
  background: rgba(16, 185, 129, 0.15);
  color: var(--emerald);
}

.lock-icon {
  margin-right: 6px;
  font-size: 0.85rem;
}

.chevron-icon {
  flex-shrink: 0;
  width: 24px;
  height: 24px;
  color: var(--text-dim);
  transition: transform 0.3s ease;
}

.module-card.active .chevron-icon {
  transform: rotate(180deg);
}

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

.module-card.active .module-content,
.module-content.expanded {
  max-height: 2000px;
}

.lessons-list {
  padding: 12px 24px 16px;
  margin-top: var(--spacing-md);
  background: rgba(10, 10, 26, 0.3);
  border-radius: 8px;
}

.lesson-item {
  margin-bottom: 4px;
}

.lesson-link {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: 10px 12px;
  border-radius: 8px;
  color: var(--text-muted);
  font-size: 0.9rem;
  transition: all 0.2s ease;
}

.lesson-link:hover {
  background: rgba(124, 92, 252, 0.1);
  color: var(--accent-bright);
}

.lesson-number {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  background: var(--accent);
  border-radius: 50%;
  font-size: 0.75rem;
  font-weight: 700;
  color: #fff;
  flex-shrink: 0;
}

.lesson-title {
  font-size: 0.95rem;
}

/* ===========================
   UNLOCK SECTION
   =========================== */

.module-unlock {
  text-align: center;
  padding: var(--spacing-2xl) var(--spacing-lg);
  background: rgba(16, 185, 129, 0.05);
  border-radius: 12px;
  margin-top: var(--spacing-md);
}

.unlock-link {
  color: var(--emerald);
  font-weight: 700;
  transition: all 0.3s ease;
}

.unlock-link:hover {
  color: var(--cyan);
}

/* ===========================
   RESOURCES SECTION
   =========================== */

.resources-section {
  padding: 60px 0;
}

.resources-subtitle {
  color: var(--text-muted);
  margin-bottom: var(--spacing-2xl);
}

.resource-badge {
  display: inline-block;
  background: rgba(124, 92, 252, 0.1);
  border: 1px solid var(--border);
  color: var(--accent-bright);
  padding: 16px 24px;
  border-radius: 12px;
  margin-bottom: var(--spacing-lg);
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.3s ease;
  cursor: pointer;
}

.resource-badge:hover {
  background: rgba(124, 92, 252, 0.2);
  border-color: var(--accent-bright);
}

/* ===========================
   CTA BANNER
   =========================== */

.cta-banner {
  background: var(--accent-gradient);
  padding: var(--spacing-2xl);
  border-radius: 16px;
  text-align: center;
  margin: var(--spacing-3xl) 0;
}

.cta-banner h3 {
  color: #fff;
  margin-bottom: var(--spacing-md);
}

.cta-button {
  background: linear-gradient(135deg, var(--accent), var(--accent-secondary));
  color: #fff;
  padding: 8px 20px;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.9rem;
  text-decoration: none;
  transition: all 0.3s ease;
  white-space: nowrap;
}

.cta-button:hover {
  box-shadow: 0 4px 15px rgba(124, 92, 252, 0.4);
  transform: translateY(-1px);
  color: #fff;
}

.cta-button-large {
  background: rgba(255, 255, 255, 0.15);
  color: #fff;
  border: 2px solid rgba(255, 255, 255, 0.3);
  padding: 16px 40px;
  font-size: 1rem;
  font-weight: 700;
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.3s ease;
  display: inline-block;
  text-decoration: none;
  margin-top: var(--spacing-md);
}

.cta-button-large:hover {
  background: rgba(255, 255, 255, 0.25);
  border-color: rgba(255, 255, 255, 0.5);
}

/* ===========================
   LESSON PAGE LAYOUT
   =========================== */

.lesson-page {
  display: flex;
  min-height: 100vh;
  flex-direction: column;
}

/* Lesson nav as narrow vertical left sidebar */
.lesson-sidebar {
  width: 200px;
  min-width: 200px;
  background: var(--surface);
  border-right: 1px solid var(--border);
  padding: 0;
  position: sticky;
  top: 60px;
  z-index: 50;
  height: calc(100vh - 60px);
  overflow-y: auto;
  overflow-x: hidden;
  -webkit-overflow-scrolling: touch;
}

.sidebar-toggle {
  display: none;
}

.sidebar-nav {
  padding: var(--spacing-md) 0;
}

.sidebar-module {
  margin-bottom: 0;
}

.sidebar-module-title {
  font-size: 0.65rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.8px;
  font-weight: 700;
  padding: var(--spacing-sm) var(--spacing-md) var(--spacing-xs);
  margin-bottom: 0;
  text-align: left;
  line-height: 1.4;
}

.sidebar-lessons {
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.sidebar-lesson {
  margin-bottom: 0;
}

.sidebar-lesson a {
  display: block;
  padding: 8px var(--spacing-md);
  color: var(--text-muted);
  font-size: 0.8rem;
  border-left: 3px solid transparent;
  border-bottom: none;
  border-radius: 0;
  transition: all 0.2s ease;
  text-decoration: none;
  line-height: 1.3;
}

.sidebar-lesson a:hover {
  color: var(--accent-bright);
  background: rgba(124, 92, 252, 0.08);
  border-left-color: rgba(124, 92, 252, 0.3);
}

.sidebar-lesson a.active {
  color: var(--accent-bright);
  background: rgba(124, 92, 252, 0.12);
  border-left-color: var(--accent);
}

.sidebar-lesson a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

/* ===========================
   LESSON CONTAINER & CONTENT
   =========================== */

.lesson-container {
  display: flex;
  flex-direction: row;
  flex: 1;
}

.lesson-content {
  flex: 1;
  min-width: 0;
  overflow-y: auto;
  padding: var(--spacing-3xl) 6vw;
}

.lesson-header {
  margin-bottom: var(--spacing-lg);
  padding-bottom: var(--spacing-md);
  border-bottom: 1px solid var(--border);
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--spacing-sm) var(--spacing-lg);
}

.lesson-header .lesson-title {
  font-size: 1.5rem;
  margin: 0;
  flex-shrink: 0;
}

.lesson-breadcrumb {
  display: none;
}

.lesson-badge {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 6px;
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.4px;
  background: rgba(16, 185, 129, 0.15);
  color: var(--emerald);
  margin: 0;
  align-self: center;
}

.lesson-meta-bar {
  display: flex;
  gap: var(--spacing-md);
  align-items: center;
  margin-left: auto;
  flex-shrink: 0;
}

.lesson-meta {
  font-size: 0.8rem;
  color: var(--text-dim);
  margin: 0;
  white-space: nowrap;
}

/* ===========================
   LESSON SECTION BLOCK
   =========================== */

.lesson-section {
  max-width: 720px;
  margin-bottom: var(--spacing-2xl);
  padding: var(--spacing-2xl);
  background: rgba(22, 22, 46, 0.3);
  border-radius: 12px;
  border: 1px solid var(--border);
  line-height: 1.8;
}

.lesson-section h3 {
  margin-bottom: var(--spacing-lg);
  color: var(--text);
}

.lesson-section p {
  margin-bottom: var(--spacing-lg);
}

.lesson-section ul,
.lesson-section ol {
  margin-left: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.lesson-section li {
  margin-bottom: var(--spacing-md);
  color: var(--text-muted);
}

/* ===========================
   QUICK CHECK COMPONENT
   =========================== */

.quick-check {
  background: rgba(34, 211, 238, 0.08);
  border: 2px solid var(--cyan);
  border-left-width: 6px;
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.quick-check:hover {
  background: rgba(34, 211, 238, 0.12);
  box-shadow: 0 8px 24px rgba(34, 211, 238, 0.15);
  transform: translateX(4px);
}

.quick-check h4 {
  color: var(--cyan);
  margin-bottom: var(--spacing-md);
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.quick-check h4::before {
  content: '⚡';
  font-size: 1.2rem;
}

.quick-check-toggle {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-sm);
  width: 100%;
  background: none;
  border: none;
  color: var(--text);
  font-size: 0.95rem;
  line-height: 1.6;
  cursor: pointer;
  padding: 0;
  text-align: left;
  font-family: inherit;
}

.quick-check-toggle:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

.toggle-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  flex-shrink: 0;
  background: rgba(34, 211, 238, 0.2);
  border-radius: 6px;
  color: var(--cyan);
  font-size: 1rem;
  font-weight: 700;
  transition: transform 0.3s ease;
  margin-top: 2px;
}

.quick-check.open .toggle-icon {
  transform: rotate(45deg);
}

.quick-check-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease;
}

.quick-check.open .quick-check-content {
  max-height: 500px;
}

.quick-check-options {
  margin-bottom: var(--spacing-md);
}

.quick-check-answer {
  padding: 12px 16px;
  background: rgba(16, 185, 129, 0.1);
  border-radius: 8px;
  color: var(--emerald);
  margin-top: var(--spacing-md);
  font-weight: 500;
}

/* ===========================
   DIAGRAM PLACEHOLDER
   =========================== */

.diagram-placeholder {
  background: linear-gradient(135deg, rgba(124, 92, 252, 0.1) 0%, rgba(34, 211, 238, 0.1) 100%);
  border: 2px dashed var(--border);
  border-radius: 12px;
  padding: 60px var(--spacing-2xl);
  text-align: center;
  margin: var(--spacing-2xl) 0;
  color: var(--text-dim);
}

.diagram-placeholder p {
  margin: 0;
}

/* ===========================
   KEY CONCEPTS CARD
   =========================== */

.key-concepts-card {
  background: linear-gradient(135deg, rgba(124, 92, 252, 0.1) 0%, rgba(34, 211, 238, 0.05) 100%);
  border: 1px solid rgba(124, 92, 252, 0.2);
  border-left: 4px solid var(--accent);
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
}

.key-concepts-card h4 {
  color: var(--accent-bright);
  margin-bottom: var(--spacing-lg);
}

.concepts-list {
  padding-left: 20px;
  list-style: disc;
}

.concepts-list li {
  margin-bottom: var(--spacing-md);
  color: var(--text-muted);
}

/* ===========================
   INFO CALLOUT
   =========================== */

.info-callout {
  background: rgba(16, 185, 129, 0.08);
  backdrop-filter: blur(20px);
  border: 1px solid rgba(16, 185, 129, 0.3);
  border-left: 5px solid var(--emerald);
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
}

.info-callout.checkpoint {
  border-left-color: var(--accent);
  background: rgba(124, 92, 252, 0.08);
  border-color: rgba(124, 92, 252, 0.3);
}

.info-callout h4 {
  margin-bottom: var(--spacing-md);
}

.info-callout p {
  margin-bottom: 0;
}

/* ===========================
   ACTIVITY SECTION
   =========================== */

.activity-section {
  background: linear-gradient(135deg, rgba(34, 211, 238, 0.1) 0%, rgba(124, 92, 252, 0.1) 100%);
  border: 2px solid var(--border-bright);
  border-radius: 16px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
}

.activity-intro {
  color: var(--text-muted);
  margin-bottom: var(--spacing-lg);
  font-size: 0.95rem;
}

.launch-activity-btn {
  background: var(--accent-gradient);
  color: #fff;
  padding: 16px 40px;
  font-size: 1rem;
  font-weight: 700;
  border: none;
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.3s ease;
  display: inline-block;
  margin: var(--spacing-lg) 0;
}

.launch-activity-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 40px rgba(124, 92, 252, 0.3);
}

.activity-resource {
  margin-top: var(--spacing-lg);
}

.download-link {
  color: var(--accent);
  font-weight: 700;
  transition: color 0.3s ease;
}

.download-link:hover {
  color: var(--cyan);
}

/* ===========================
   QUIZ SECTION
   =========================== */

.quiz-section {
  margin: var(--spacing-2xl) 0;
}

.quiz-question {
  background: rgba(22, 22, 46, 0.6);
  border: 1.5px solid var(--border);
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin-bottom: var(--spacing-2xl);
  transition: all 0.3s ease;
}

.quiz-question:hover {
  border-color: var(--border-bright);
  background: rgba(26, 26, 53, 0.7);
}

.quiz-question-text {
  font-weight: 600;
  color: var(--text);
  margin-bottom: var(--spacing-lg);
  display: flex;
  gap: var(--spacing-md);
}

.quiz-question-text::before {
  content: attr(data-number);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: var(--accent-gradient);
  border-radius: 8px;
  color: #fff;
  font-weight: 700;
  font-size: 0.9rem;
}

.quiz-options {
  margin-bottom: var(--spacing-lg);
}

.quiz-option {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: 14px 16px;
  margin-bottom: var(--spacing-md);
  background: rgba(124, 92, 252, 0.05);
  border: 1.5px solid transparent;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.quiz-option:hover {
  background: rgba(124, 92, 252, 0.1);
  border-color: var(--accent);
}

.quiz-option:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(124, 92, 252, 0.2);
}

.quiz-option input[type="radio"] {
  margin: 0;
  cursor: pointer;
  accent-color: var(--accent);
}

.quiz-option.selected {
  background: rgba(16, 185, 129, 0.15);
  border-color: var(--emerald);
}

.quiz-option.selected.incorrect {
  background: rgba(249, 112, 102, 0.15);
  border-color: var(--coral);
}

.quiz-check-btn {
  background: var(--accent-gradient);
  color: #fff;
  padding: 12px 32px;
  font-weight: 700;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  font-size: 0.95rem;
  transition: all 0.3s ease;
}

.quiz-check-btn:hover {
  box-shadow: 0 8px 24px rgba(124, 92, 252, 0.3);
  transform: translateY(-2px);
}

.quiz-feedback {
  display: none;
  margin-top: var(--spacing-lg);
  padding: 16px;
  border-radius: 10px;
  animation: slideDown 0.3s ease-out;
}

.quiz-feedback.show {
  display: block;
}

.quiz-feedback.correct {
  background: rgba(16, 185, 129, 0.15);
  border: 1px solid var(--emerald);
  color: var(--emerald);
}

.quiz-feedback.incorrect {
  background: rgba(249, 112, 102, 0.15);
  border: 1px solid var(--coral);
  color: var(--coral);
}

/* ===========================
   REFLECTION CARD
   =========================== */

.reflection-card {
  background: rgba(245, 158, 11, 0.08);
  border: 1px solid rgba(245, 158, 11, 0.3);
  border-left: 5px solid var(--amber);
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
}

.reflection-card h4 {
  color: var(--amber);
  margin-bottom: var(--spacing-lg);
}

.reflection-input {
  width: 100%;
  background: rgba(10, 10, 26, 0.5);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: var(--spacing-lg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 0.95rem;
  resize: vertical;
  min-height: 120px;
  transition: all 0.3s ease;
}

.reflection-input:focus {
  outline: none;
  border-color: var(--amber);
  background: rgba(10, 10, 26, 0.8);
  box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.1);
}

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

/* ===========================
   CHECKPOINT & MILESTONES
   =========================== */

.checkpoint-note {
  color: var(--text-muted);
  font-style: italic;
}

.example-checkpoint {
  background: linear-gradient(135deg, rgba(16, 185, 129, 0.1) 0%, rgba(34, 211, 238, 0.1) 100%);
  border: 1.5px dashed var(--emerald);
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
}

.example-checkpoint h4 {
  color: var(--emerald);
  margin-bottom: var(--spacing-lg);
}

.project-checkpoint {
  background: linear-gradient(135deg, rgba(16, 185, 129, 0.15) 0%, rgba(34, 211, 238, 0.1) 100%);
  border: 2px solid var(--emerald);
  border-radius: 16px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
  text-align: center;
}

.project-checkpoint h3 {
  color: var(--emerald);
  margin-bottom: var(--spacing-lg);
}

.project-checkpoint::before {
  content: '✓';
  display: block;
  font-size: 3rem;
  color: var(--emerald);
  margin-bottom: var(--spacing-md);
}

/* ===========================
   COMING NEXT SECTION
   =========================== */

.coming-next {
  background: rgba(22, 22, 46, 0.6);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin-top: var(--spacing-3xl);
}

.coming-next h3,
.coming-next h4 {
  color: var(--text);
  margin-bottom: var(--spacing-lg);
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.coming-next h3::before,
.coming-next h4::before {
  content: '→';
  font-size: 1.3rem;
  color: var(--accent-bright);
}

.continue-btn {
  display: inline-block;
  background: linear-gradient(135deg, var(--accent), var(--accent-secondary));
  color: #fff;
  border: none;
  padding: 14px 32px;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  font-weight: 600;
  font-size: 1rem;
  text-decoration: none;
  margin-top: var(--spacing-lg);
}

.continue-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(124, 92, 252, 0.4);
  color: #fff;
}

.continue-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.previous-btn {
  background: var(--surface2);
  color: var(--text-muted);
  border: 1px solid var(--border);
  padding: 12px 24px;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 600;
  text-decoration: none;
  display: inline-block;
}

.previous-btn:hover {
  background: var(--surface3);
  border-color: var(--border-bright);
  color: var(--text);
}

.coming-soon {
  color: var(--text-dim);
  font-style: italic;
}

/* ===========================
   LESSON STEPPER
   =========================== */

/* Hide all steps by default; JS adds .step-active to show one */
.lesson-step {
  display: none;
  animation: stepFadeIn 0.35s ease-out;
}

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

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

/* Top navigation: dots + label — compact bar below header */
.stepper-nav {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-sm) 0 var(--spacing-md);
  margin-bottom: var(--spacing-md);
}

.stepper-dots {
  display: flex;
  gap: 8px;
  align-items: center;
}

.stepper-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  border: 2px solid var(--border-bright);
  background: transparent;
  cursor: pointer;
  transition: all 0.25s ease;
  padding: 0;
}

.stepper-dot:hover {
  border-color: var(--accent);
  transform: scale(1.2);
}

.stepper-dot.active {
  background: var(--accent);
  border-color: var(--accent);
  box-shadow: 0 0 8px rgba(124, 92, 252, 0.5);
  transform: scale(1.15);
}

.stepper-dot.completed {
  background: var(--green);
  border-color: var(--green);
}

.stepper-label {
  font-size: 0.78rem;
  color: var(--text-dim);
  font-weight: 500;
}

/* Bottom navigation: prev / page info / next */
.stepper-bottom-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-2xl) 0 var(--spacing-lg);
  margin-top: var(--spacing-2xl);
  border-top: 1px solid var(--border);
}

.stepper-btn {
  background: rgba(124, 92, 252, 0.12);
  color: var(--accent-bright);
  border: 1px solid rgba(124, 92, 252, 0.25);
  padding: 12px 28px;
  border-radius: 10px;
  cursor: pointer;
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.25s ease;
}

.stepper-btn:hover {
  background: rgba(124, 92, 252, 0.22);
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(124, 92, 252, 0.2);
}

.stepper-next {
  background: linear-gradient(135deg, var(--accent), var(--accent-secondary));
  color: #fff;
  border-color: transparent;
}

.stepper-next:hover {
  box-shadow: 0 6px 20px rgba(124, 92, 252, 0.4);
  color: #fff;
}

.stepper-page-info {
  font-size: 0.85rem;
  color: var(--text-dim);
  font-weight: 500;
}

@media (max-width: 768px) {
  .stepper-btn {
    padding: 10px 20px;
    font-size: 0.85rem;
  }

  .stepper-dots {
    gap: 6px;
  }

  .stepper-dot {
    width: 9px;
    height: 9px;
  }

  .lesson-header {
    flex-direction: column;
    gap: var(--spacing-xs);
    align-items: flex-start;
  }

  .lesson-header .lesson-title {
    font-size: 1.25rem;
  }

  .lesson-meta-bar {
    margin-left: 0;
  }
}

/* ===========================
   FAIL SCENARIO
   =========================== */

.fail-scenario {
  background: rgba(249, 112, 102, 0.08);
  border: 1px solid rgba(249, 112, 102, 0.3);
  border-left: 5px solid var(--coral);
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
}

.fail-title {
  font-weight: 700;
  color: var(--coral);
  margin-bottom: var(--spacing-md);
}

.fail-description {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: var(--spacing-lg);
}

.fail-reveal-btn {
  background: rgba(249, 112, 102, 0.2);
  color: var(--coral);
  border: 1px solid var(--coral);
  padding: 10px 20px;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 600;
  transition: all 0.3s ease;
  font-size: 0.9rem;
}

.fail-reveal-btn:hover {
  background: var(--coral);
  color: #fff;
}

.fail-answer {
  display: none;
  margin-top: var(--spacing-lg);
  padding: var(--spacing-lg);
  background: rgba(10, 10, 26, 0.5);
  border-radius: 8px;
  animation: slideDown 0.3s ease-out;
}

.fail-answer.revealed,
.fail-scenario.revealed .fail-answer {
  display: block;
}

.reveal-text {
  display: none;
}

/* ===========================
   TRACK CARDS
   =========================== */

.track-cards {
  display: grid;
  gap: var(--spacing-lg);
}

.track-difficulty {
  font-size: 0.8rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-top: var(--spacing-md);
}

.track-tools {
  font-size: 0.85rem;
  color: var(--text-dim);
  margin-top: var(--spacing-md);
}

/* ===========================
   BRAINSTORM STEPS
   =========================== */

.brainstorm-steps {
  margin: var(--spacing-2xl) 0;
  counter-reset: step;
}

.brainstorm-step {
  display: flex;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-2xl);
  padding-bottom: var(--spacing-2xl);
  border-bottom: 1px solid var(--border);
}

.brainstorm-step:last-child {
  border-bottom: none;
}

.brainstorm-step::before {
  content: counter(step);
  counter-increment: step;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: var(--accent-gradient);
  border-radius: 10px;
  color: #fff;
  font-weight: 700;
  flex-shrink: 0;
}

/* ===========================
   AI PROMPT BLOCK
   =========================== */

.ai-prompt-block {
  background: #0d0d20;
  border: 1px solid var(--border);
  border-top: 3px solid var(--accent-gradient);
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
  font-family: 'Courier New', monospace;
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--text-muted);
  position: relative;
  overflow: hidden;
}

.ai-prompt-block::after {
  content: 'Copy';
  position: absolute;
  top: var(--spacing-md);
  right: var(--spacing-md);
  background: var(--accent);
  color: #fff;
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.2s ease;
  font-family: var(--font-body);
}

.ai-prompt-block:hover::after {
  background: var(--accent-bright);
}

/* ===========================
   TRACK TABS
   =========================== */

.track-tabs {
  background: rgba(22, 22, 46, 0.6);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: var(--spacing-lg);
  margin: var(--spacing-2xl) 0;
}

.track-tabs-nav {
  display: flex;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-2xl);
  border-bottom: 1px solid var(--border);
}

.track-tabs-button {
  background: none;
  border: none;
  color: var(--text-muted);
  padding: var(--spacing-md) var(--spacing-lg);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  position: relative;
  transition: all 0.3s ease;
}

.track-tabs-button:hover {
  color: var(--accent-bright);
}

.track-tabs-button.active {
  color: var(--accent-bright);
}

.track-tabs-button.active::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--accent-gradient);
}

.track-tabs-content {
  display: none;
}

.track-tabs-content.active {
  display: block;
  animation: fadeUpIn 0.3s ease-out;
}

/* ===========================
   LESSON PROGRESS BAR
   =========================== */

.lesson-progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--border);
  z-index: 99;
}

.lesson-progress-fill {
  height: 100%;
  background: var(--accent-gradient);
  transition: width 0.2s ease-out;
  width: 0%;
}

/* ===========================
   CONTENT STEP
   =========================== */

.content-step {
  background: rgba(22, 22, 46, 0.6);
  border: 1px solid var(--border);
  border-left: 5px solid var(--accent);
  border-radius: 12px;
  padding: var(--spacing-2xl);
  margin: var(--spacing-2xl) 0;
  position: relative;
}

.content-step::before {
  content: attr(data-step);
  position: absolute;
  left: -30px;
  top: var(--spacing-2xl);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 50px;
  height: 50px;
  background: var(--accent-gradient);
  border-radius: 50%;
  color: #fff;
  font-weight: 700;
  font-size: 1.2rem;
}

.content-step h3 {
  margin-bottom: var(--spacing-lg);
  color: var(--accent-bright);
}

.content-step p {
  margin-bottom: var(--spacing-lg);
}

.content-step:not(:last-child)::after {
  content: '';
  position: absolute;
  left: 17px;
  bottom: -30px;
  width: 2px;
  height: 30px;
  background: var(--border);
}

/* ===========================
   WHAT'S INCLUDED SECTION
   =========================== */

.whats-included {
  background: var(--bg-primary);
  padding: 80px 0;
  position: relative;
}

.included-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-2xl);
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.included-item {
  background: rgba(22, 22, 46, 0.6);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: var(--spacing-2xl);
  text-align: center;
  transition: all 0.3s ease;
}

.included-item:hover {
  border-color: var(--border-bright);
  background: rgba(26, 26, 53, 0.8);
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(124, 92, 252, 0.15);
}

.included-icon {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-lg);
  display: block;
}

.included-item h4 {
  font-size: 1.1rem;
  color: var(--text);
  margin-bottom: var(--spacing-md);
  text-transform: none;
  letter-spacing: normal;
}

.included-item p {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 0;
  line-height: 1.6;
}

/* ===========================
   CTA BUTTONS GROUP
   =========================== */

.cta-buttons {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  flex-wrap: wrap;
  margin-top: var(--spacing-xl);
}

/* ===========================
   FOOTER
   =========================== */

.footer {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: var(--spacing-3xl) 0;
  margin-top: var(--spacing-3xl);
}

.footer-content {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
  color: var(--text-muted);
  text-align: center;
}

.footer-content p {
  margin-bottom: var(--spacing-lg);
}

/* ===========================
   ANIMATIONS
   =========================== */

.fadeUp {
  opacity: 0;
  transform: translateY(20px);
  animation: fadeUpIn 0.8s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

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

/* ===========================
   RESPONSIVE DESIGN
   =========================== */

@media (max-width: 768px) {
  .navbar-menu, .nav-links, .navbar-links {
    gap: var(--spacing-md);
    font-size: 0.85rem;
  }

  .navbar-cta {
    padding: 6px 14px;
    font-size: 0.8rem;
  }

  .hero {
    padding: 80px 0 60px;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: center;
  }

  .hero-stats {
    gap: var(--spacing-2xl);
  }

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

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

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

  .cta-buttons {
    flex-direction: column;
    align-items: center;
  }

  .cta-buttons .btn {
    width: 100%;
    max-width: 300px;
  }

  .lesson-page {
    flex-direction: column;
  }

  .lesson-container {
    flex-direction: column;
  }

  .lesson-sidebar {
    width: 100%;
    min-width: unset;
    height: auto;
    border-right: none;
    border-bottom: 1px solid var(--border);
    top: 56px;
    overflow: visible;
    position: sticky;
    z-index: 50;
  }

  /* Hamburger toggle — visible on mobile */
  .sidebar-toggle {
    display: flex;
    align-items: center;
    gap: 5px;
    padding: 12px var(--spacing-md);
    background: var(--surface);
    cursor: pointer;
  }

  .sidebar-toggle span {
    display: block;
    width: 18px;
    height: 2px;
    background: var(--text-muted);
    border-radius: 2px;
    transition: all 0.2s ease;
  }

  .sidebar-toggle:hover span {
    background: var(--accent-bright);
  }

  /* Nav content — hidden by default on mobile */
  .sidebar-nav {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease;
    padding: 0 var(--spacing-md);
  }

  /* Revealed when sidebar has .open class */
  .lesson-sidebar.open .sidebar-nav {
    max-height: 400px;
    overflow-y: auto;
    padding: 0 var(--spacing-md) var(--spacing-md);
  }

  .sidebar-lessons {
    flex-direction: column;
    flex-wrap: nowrap;
    gap: 2px;
    padding-bottom: 0;
  }

  .sidebar-lesson a {
    border-left: 3px solid transparent;
    border-bottom: none;
    border-radius: 0;
    white-space: normal;
    padding: 10px var(--spacing-md);
    font-size: 0.9rem;
  }

  .sidebar-lesson a:hover {
    border-left-color: rgba(124, 92, 252, 0.3);
  }

  .sidebar-lesson a.active {
    border-left-color: var(--accent);
    border-bottom-color: transparent;
  }

  .sidebar-module-title {
    text-align: left;
    padding: var(--spacing-sm) var(--spacing-md) var(--spacing-xs);
    white-space: normal;
  }

  .lesson-content {
    padding: var(--spacing-2xl) var(--spacing-lg);
  }

  .section-title {
    font-size: 1.8rem;
  }

  h1 {
    font-size: 2rem;
  }

  h2 {
    font-size: 1.5rem;
  }

  .pricing-card {
    max-width: 100%;
  }

  .cta-title {
    font-size: 1.5rem;
  }

  .lessons-list {
    padding: 10px 16px 12px;
  }

  .quiz-question-text {
    flex-direction: column;
    align-items: flex-start;
  }

  .quick-check {
    padding: var(--spacing-lg);
  }

  .track-tabs-nav {
    flex-wrap: wrap;
  }

  .content-step::before {
    position: static;
    margin-bottom: var(--spacing-md);
    width: 40px;
    height: 40px;
  }

  .content-step:not(:last-child)::after {
    display: none;
  }
}

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

  .hero-stats {
    gap: var(--spacing-2xl);
  }

  .lesson-sidebar {
    width: 170px;
    min-width: 170px;
  }

  .sidebar-lesson a {
    font-size: 0.75rem;
    padding: 6px var(--spacing-sm);
  }

  .sidebar-module-title {
    font-size: 0.6rem;
  }

  .lesson-content {
    padding: var(--spacing-2xl) var(--spacing-xl);
  }

  h1 {
    font-size: 2.5rem;
  }

  h2 {
    font-size: 2rem;
  }
}

/* ===========================
   UNLOCK PAGE
   =========================== */

.unlock-page {
  min-height: 80vh;
  display: flex;
  align-items: center;
  padding: 120px 0 80px;
}

.unlock-card {
  max-width: 560px;
  margin: 0 auto;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 48px 40px;
}

.unlock-header {
  text-align: center;
  margin-bottom: 32px;
}

.unlock-header h1 {
  font-size: 2rem;
  margin-bottom: 12px;
}

.unlock-subtitle {
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.6;
}

.unlock-form {
  margin-bottom: 32px;
}

.unlock-input-group {
  display: flex;
  gap: 12px;
}

.unlock-input-group input {
  flex: 1;
  padding: 14px 18px;
  background: var(--background);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--text);
  font-family: var(--font-body);
  font-size: 1rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  outline: none;
  transition: border-color 0.2s ease;
}

.unlock-input-group input:focus {
  border-color: var(--accent);
}

.unlock-input-group input::placeholder {
  text-transform: none;
  letter-spacing: normal;
  color: var(--text-dim);
}

.unlock-message {
  margin-top: 16px;
  padding: 12px 16px;
  border-radius: 8px;
  font-size: 0.9rem;
  line-height: 1.5;
}

.unlock-error {
  background: rgba(239, 68, 68, 0.1);
  border: 1px solid rgba(239, 68, 68, 0.3);
  color: #f87171;
}

.unlock-success {
  background: rgba(52, 211, 153, 0.1);
  border: 1px solid rgba(52, 211, 153, 0.3);
  color: #34d399;
}

.unlock-divider {
  height: 1px;
  background: var(--border);
  margin: 32px 0;
}

.unlock-purchase {
  text-align: center;
}

.unlock-purchase h3 {
  font-size: 1.2rem;
  margin-bottom: 12px;
}

.unlock-purchase p {
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.6;
  margin-bottom: 20px;
}

.unlock-purchase .btn {
  margin-bottom: 16px;
}

.unlock-note {
  font-size: 0.85rem !important;
  color: var(--text-dim) !important;
}

/* Shake animation for wrong code */
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-8px); }
  75% { transform: translateX(8px); }
}
.shake {
  animation: shake 0.3s ease-in-out;
}

/* ===========================
   LOCKED MODULE STATES
   =========================== */

.module-locked {
  opacity: 0.7;
}

.module-locked .module-header {
  cursor: pointer;
}

.locked-message {
  list-style: none;
  padding: 20px 24px;
}

.locked-content {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.lock-icon {
  font-size: 1.1rem;
}

.locked-content span:nth-child(2) {
  color: var(--text-muted);
  font-size: 0.95rem;
}

.unlock-link {
  color: var(--accent-bright);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  margin-left: auto;
}

.unlock-link:hover {
  text-decoration: underline;
}