:root {
  --bg: #0a0a0f;
  --bg-surface: #12121a;
  --bg-card: #1a1a26;
  --fg: #e8e8ef;
  --fg-dim: #8888a0;
  --accent: #00d4ff;
  --accent-glow: rgba(0, 212, 255, 0.15);
  --accent-warm: #ff6b35;
  --border: rgba(255, 255, 255, 0.06);
  --font-display: 'Space Grotesk', sans-serif;
  --font-body: 'DM Sans', sans-serif;
  --max-width: 1100px;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* === HERO === */
.hero {
  position: relative;
  padding: 120px 24px 80px;
  overflow: hidden;
  text-align: center;
}

.hero-inner {
  position: relative;
  z-index: 2;
  max-width: var(--max-width);
  margin: 0 auto;
}

.hero-badge {
  display: inline-block;
  padding: 6px 16px;
  background: var(--accent-glow);
  border: 1px solid rgba(0, 212, 255, 0.3);
  border-radius: 100px;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 2px;
  color: var(--accent);
  margin-bottom: 32px;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(40px, 7vw, 72px);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -0.03em;
  color: var(--fg);
  margin-bottom: 24px;
}

.hero h1 .highlight {
  background: linear-gradient(135deg, var(--accent), #00ffaa);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.lede {
  font-size: 19px;
  color: var(--fg-dim);
  max-width: 640px;
  margin: 0 auto 48px;
  line-height: 1.7;
}

.hero-stats {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 40px;
  flex-wrap: wrap;
}

.stat { text-align: center; }

.stat-num {
  display: block;
  font-family: var(--font-display);
  font-size: 36px;
  font-weight: 700;
  color: var(--accent);
  line-height: 1.2;
}

.stat-label {
  display: block;
  font-size: 13px;
  color: var(--fg-dim);
  margin-top: 4px;
  line-height: 1.4;
}

.stat-divider {
  width: 1px;
  height: 48px;
  background: var(--border);
}

.hero-glow {
  position: absolute;
  top: -200px;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, rgba(0, 212, 255, 0.08) 0%, transparent 60%);
  pointer-events: none;
  z-index: 1;
}

/* === PROBLEM === */
.problem {
  padding: 80px 24px;
  background: var(--bg-surface);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.problem-inner {
  max-width: 720px;
  margin: 0 auto;
}

.problem h2 {
  font-family: var(--font-display);
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 700;
  margin-bottom: 32px;
  letter-spacing: -0.02em;
}

.problem-text {
  font-size: 18px;
  color: var(--fg-dim);
  margin-bottom: 20px;
  line-height: 1.7;
}

.problem-text.accent {
  color: var(--fg);
  font-weight: 500;
  border-left: 3px solid var(--accent);
  padding-left: 20px;
  margin-top: 32px;
}

/* === FEATURES === */
.features {
  padding: 100px 24px;
}

.features-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.features-header {
  margin-bottom: 56px;
}

.features-header h2 {
  font-family: var(--font-display);
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 36px;
  transition: border-color 0.2s;
}

.feature-card:hover {
  border-color: rgba(0, 212, 255, 0.2);
}

.feature-icon {
  font-size: 28px;
  margin-bottom: 16px;
}

.feature-card h3 {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

.feature-card p {
  font-size: 15px;
  color: var(--fg-dim);
  line-height: 1.65;
}

/* === MATH === */
.math {
  padding: 80px 24px;
  background: var(--bg-surface);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.math-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  text-align: center;
}

.math h2 {
  font-family: var(--font-display);
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 700;
  margin-bottom: 48px;
  letter-spacing: -0.02em;
}

.math-grid {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 32px;
  flex-wrap: wrap;
}

.math-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 36px;
  width: 320px;
  text-align: left;
}

.math-card.active {
  border-color: var(--accent);
  box-shadow: 0 0 40px rgba(0, 212, 255, 0.1);
}

.math-label {
  font-family: var(--font-display);
  font-size: 14px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--fg-dim);
  margin-bottom: 20px;
}

.math-card.active .math-label {
  color: var(--accent);
}

.math-breakdown p {
  font-size: 16px;
  color: var(--fg-dim);
  padding: 8px 0;
  border-bottom: 1px solid var(--border);
}

.math-breakdown p:last-child {
  border-bottom: none;
  padding-top: 16px;
}

.math-result {
  font-family: var(--font-display);
  font-size: 24px !important;
  font-weight: 700;
  color: var(--fg) !important;
}

.math-result.dim {
  color: var(--fg-dim) !important;
}

.math-card.active .math-result {
  color: var(--accent) !important;
}

.math-arrow {
  font-size: 32px;
  color: var(--fg-dim);
}

.math-footnote {
  margin-top: 32px;
  font-size: 13px;
  color: var(--fg-dim);
}

/* === CLOSING === */
.closing {
  padding: 100px 24px;
  text-align: center;
}

.closing-inner {
  max-width: 720px;
  margin: 0 auto;
}

.closing h2 {
  font-family: var(--font-display);
  font-size: clamp(28px, 4.5vw, 44px);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin-bottom: 32px;
}

.closing-text {
  font-size: 18px;
  color: var(--fg-dim);
  line-height: 1.7;
  margin-bottom: 20px;
}

.closing-text:last-child {
  color: var(--fg);
  font-weight: 500;
}

/* === FOOTER === */
.site-footer {
  padding: 48px 24px;
  border-top: 1px solid var(--border);
  text-align: center;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.footer-brand {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 4px;
}

.footer-tagline {
  font-size: 14px;
  color: var(--fg-dim);
}

/* === CTA BUTTONS (landing) === */
.hero-cta {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 16px;
  margin-bottom: 48px;
  flex-wrap: wrap;
}

.cta-btn-primary {
  display: inline-block;
  padding: 15px 36px;
  background: var(--accent);
  color: #000;
  font-family: var(--font-display);
  font-size: 16px;
  font-weight: 700;
  border-radius: 12px;
  text-decoration: none;
  transition: opacity 0.2s, transform 0.15s;
  letter-spacing: -0.01em;
}

.cta-btn-primary:hover { opacity: 0.9; transform: translateY(-1px); }

.cta-btn-ghost {
  display: inline-block;
  padding: 14px 28px;
  background: none;
  color: var(--fg-dim);
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 500;
  border: 1px solid var(--border);
  border-radius: 12px;
  text-decoration: none;
  transition: border-color 0.2s, color 0.2s;
}

.cta-btn-ghost:hover { border-color: var(--fg-dim); color: var(--fg); }

.closing-cta {
  margin-top: 40px;
}

/* === RESPONSIVE === */
@media (max-width: 768px) {
  .hero { padding: 80px 20px 60px; }
  
  .hero-stats { gap: 24px; }
  
  .stat-divider { display: none; }
  
  .features-grid {
    grid-template-columns: 1fr;
  }
  
  .math-grid {
    flex-direction: column;
  }
  
  .math-arrow {
    transform: rotate(90deg);
  }
  
  .math-card {
    width: 100%;
    max-width: 360px;
  }
}

@media (max-width: 480px) {
  .hero { padding: 60px 16px 48px; }
  
  .hero-stats {
    flex-direction: column;
    gap: 20px;
  }
  
  .feature-card { padding: 24px; }
  
  .problem { padding: 60px 16px; }
  
  .features { padding: 60px 16px; }
  
  .math { padding: 60px 16px; }
  
  .closing { padding: 60px 16px; }
}