:root {
  --bg: #0a0a0a;
  --bg-elevated: #111111;
  --bg-card: #161616;
  --fg: #e8e8e8;
  --fg-muted: #888888;
  --fg-dim: #555555;
  --accent: #00ff88;
  --accent-dim: rgba(0, 255, 136, 0.1);
  --accent-border: rgba(0, 255, 136, 0.2);
  --border: rgba(255, 255, 255, 0.06);
  --font-display: 'Space Grotesk', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', monospace;
}

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

html {
  scroll-behavior: smooth;
}

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

.accent {
  color: var(--accent);
}

.section-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent);
  margin-bottom: 1.5rem;
  opacity: 0.8;
}

/* ===== HERO ===== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 6rem 2rem 4rem;
  overflow: hidden;
}

.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.02) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.02) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
}

.hero-inner {
  max-width: 900px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent);
  border: 1px solid var(--accent-border);
  background: var(--accent-dim);
  padding: 0.4rem 1rem;
  border-radius: 100px;
  margin-bottom: 2.5rem;
}

.hero h1 {
  font-size: clamp(3rem, 8vw, 6rem);
  font-weight: 700;
  line-height: 1.05;
  letter-spacing: -0.03em;
  margin-bottom: 2rem;
}

.lede {
  font-size: 1.15rem;
  color: var(--fg-muted);
  max-width: 640px;
  line-height: 1.7;
  margin-bottom: 3.5rem;
}

.hero-stats {
  display: flex;
  align-items: center;
  gap: 2rem;
  flex-wrap: wrap;
}

.stat {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.stat-num {
  font-family: var(--font-mono);
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--fg);
}

.stat-label {
  font-size: 0.8rem;
  color: var(--fg-dim);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.stat-divider {
  width: 1px;
  height: 40px;
  background: var(--border);
}

/* ===== PROBLEM ===== */
.problem {
  padding: 8rem 2rem;
  background: var(--bg);
}

.problem-inner {
  max-width: 1000px;
  margin: 0 auto;
}

.problem h2 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 4rem;
  max-width: 700px;
}

.problem-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.problem-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem;
  transition: border-color 0.3s;
}

.problem-card:hover {
  border-color: var(--accent-border);
}

.problem-icon {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  margin-bottom: 1rem;
  opacity: 0.6;
}

.problem-card h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 0.6rem;
}

.problem-card p {
  font-size: 0.95rem;
  color: var(--fg-muted);
  line-height: 1.6;
}

/* ===== SERVICES ===== */
.services {
  padding: 8rem 2rem;
  background: var(--bg-elevated);
}

.services-inner {
  max-width: 900px;
  margin: 0 auto;
}

.services h2 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 4rem;
}

.services-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.service-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--border);
  gap: 1rem;
  transition: background 0.2s;
}

.service-row:first-child {
  border-top: 1px solid var(--border);
}

.service-name {
  font-weight: 600;
  font-size: 1.05rem;
  flex-shrink: 0;
}

.service-arrow {
  color: var(--accent);
  font-size: 1.2rem;
  flex-shrink: 0;
  opacity: 0.5;
}

.service-result {
  font-size: 0.9rem;
  color: var(--fg-muted);
  text-align: right;
}

/* ===== MATH ===== */
.math {
  padding: 8rem 2rem;
  background: var(--bg);
}

.math-inner {
  max-width: 900px;
  margin: 0 auto;
}

.math h2 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 3rem;
}

.math-block {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: start;
}

.equation {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem;
  font-family: var(--font-mono);
}

.eq-line {
  display: flex;
  justify-content: space-between;
  padding: 0.75rem 0;
  font-size: 0.95rem;
}

.eq-label {
  color: var(--fg-muted);
}

.eq-value {
  color: var(--fg);
  font-weight: 500;
}

.eq-divider {
  height: 1px;
  background: var(--accent-border);
  margin: 0.5rem 0;
}

.eq-line.result .eq-value {
  color: var(--accent);
  font-weight: 600;
}

.math-note p {
  font-size: 1.05rem;
  color: var(--fg-muted);
  line-height: 1.7;
  margin-bottom: 1rem;
}

.math-note p:last-child {
  color: var(--fg);
  font-weight: 500;
}

/* ===== CLOSING ===== */
.closing {
  padding: 8rem 2rem;
  background: var(--bg-elevated);
  text-align: center;
}

.closing-inner {
  max-width: 750px;
  margin: 0 auto;
}

.closing h2 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin-bottom: 2rem;
}

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

/* ===== FOOTER ===== */
.site-footer {
  padding: 3rem 2rem;
  border-top: 1px solid var(--border);
  background: var(--bg);
}

.footer-inner {
  max-width: 900px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-brand {
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: -0.02em;
}

.footer-contact {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--fg-dim);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .hero {
    min-height: auto;
    padding: 5rem 1.5rem 3rem;
  }

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

  .service-row {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.4rem;
  }

  .service-result {
    text-align: left;
  }

  .service-arrow {
    display: none;
  }

  .math-block {
    grid-template-columns: 1fr;
  }

  .hero-stats {
    gap: 1.5rem;
  }

  .stat-divider {
    display: none;
  }

  .problem,
  .services,
  .math,
  .closing {
    padding: 5rem 1.5rem;
  }

  .footer-inner {
    flex-direction: column;
    gap: 0.5rem;
    text-align: center;
  }
}