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

:root {
  --bg: #ffffff;
  --fg: #111111;
  --muted: #666666;
  --border: #e0e0e0;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --surface: #f9fafb;
}

[data-theme="dark"] {
  --bg: #0a0a0a;
  --fg: #f0f0f0;
  --muted: #999999;
  --border: #2a2a2a;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --surface: #141414;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--fg);
  min-height: 100vh;
  line-height: 1.6;
  transition: background .3s, color .3s;
}

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Nav */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.logo {
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--fg);
  text-decoration: none;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.nav-link {
  background: none;
  border: none;
  font: inherit;
  font-size: .9rem;
  font-weight: 500;
  color: var(--muted);
  cursor: pointer;
  padding: .4rem .75rem;
  border-radius: 6px;
  transition: color .2s, background .2s;
}

.nav-link:hover {
  color: var(--fg);
  background: var(--surface);
}

/* Hero */
.hero {
  padding: 5rem 0 4.5rem;
  text-align: center;
}

.hero h1 {
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.1;
  max-width: 18ch;
  margin: 0 auto 1.5rem;
}

.hero-sub {
  font-size: clamp(1.05rem, 2vw, 1.2rem);
  color: var(--muted);
  max-width: 42rem;
  margin: 0 auto 2.5rem;
  line-height: 1.7;
}

/* Buttons */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: .85rem 1.75rem;
  background: var(--accent);
  color: #ffffff;
  border: none;
  border-radius: 8px;
  font: inherit;
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .2s, transform .15s;
}

.btn-primary:hover {
  background: var(--accent-hover);
}

.btn-primary:active {
  transform: scale(.98);
}

/* Sections */
section {
  padding: 4.5rem 0;
}

.section-title {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  text-align: center;
  margin-bottom: 3rem;
}

/* Features */
.features {
  border-top: 1px solid var(--border);
  background: var(--surface);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.feature-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem 1.75rem;
  transition: border-color .2s;
}

.feature-card:hover {
  border-color: color-mix(in srgb, var(--fg) 20%, var(--border));
}

.feature-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.25rem;
  color: var(--accent);
}

.feature-icon svg {
  width: 24px;
  height: 24px;
}

.feature-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: .5rem;
}

.feature-card p {
  font-size: .925rem;
  color: var(--muted);
  line-height: 1.65;
}

/* How it works */
.how-it-works {
  border-top: 1px solid var(--border);
}

.steps {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  counter-reset: none;
}

.step {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.step-num {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: .875rem;
  font-weight: 600;
  color: var(--accent);
  flex-shrink: 0;
}

.step-content h3 {
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: .4rem;
}

.step-content p {
  font-size: .925rem;
  color: var(--muted);
  line-height: 1.65;
}

/* Final CTA */
.final-cta {
  border-top: 1px solid var(--border);
  background: var(--surface);
  text-align: center;
}

.final-cta h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: .75rem;
}

.final-cta-sub {
  color: var(--muted);
  font-size: 1rem;
  margin-bottom: 2rem;
}

/* Footer */
.footer {
  border-top: 1px solid var(--border);
  padding: 2rem 0;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.footer a {
  color: var(--muted);
  text-decoration: none;
  font-size: .9rem;
  transition: color .2s;
}

.footer a:hover {
  color: var(--fg);
}

.footer-copy {
  font-size: .85rem;
  color: var(--muted);
}

/* Theme toggle */
.theme-toggle {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  background: var(--bg);
  border: 1.5px solid var(--border);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  cursor: pointer;
  color: var(--fg);
  z-index: 100;
  transition: border-color .2s;
}

.theme-toggle:hover {
  border-color: var(--fg);
}

/* Responsive */
@media (max-width: 768px) {
  .hero {
    padding: 3.5rem 0 3rem;
  }

  .hero h1 {
    max-width: none;
  }

  section {
    padding: 3.5rem 0;
  }

  .feature-grid,
  .steps {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }

  .feature-card {
    padding: 1.5rem;
  }

  .step {
    flex-direction: row;
    align-items: flex-start;
  }

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