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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: #1a1a1a;
  background: #ffffff;
  line-height: 1.6;
}

nav {
  background: #ffffff;
  border-bottom: 1px solid #e5e7eb;
  padding: 1rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo {
  font-weight: 700;
  font-size: 1.25rem;
  color: #0369a1;
  text-decoration: none;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 1.5rem;
  align-items: center;
}

nav a {
  color: #374151;
  text-decoration: none;
  font-size: 0.95rem;
}

nav a:hover {
  color: #0369a1;
}

main {
  max-width: 780px;
  margin: 0 auto;
  padding: 3rem 1.5rem;
}

.hero {
  text-align: center;
  padding: 2rem 0 3rem;
}

.hero h1 {
  font-size: 2.5rem;
  margin-bottom: 0.5rem;
}

.hero .tagline {
  color: #6b7280;
  font-size: 1.25rem;
  margin-bottom: 1.5rem;
}

section {
  margin-bottom: 2.5rem;
}

h1 {
  font-size: 2rem;
  margin-bottom: 1rem;
  color: #0f172a;
}

h2 {
  font-size: 1.5rem;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
  color: #0f172a;
}

p, ul, ol {
  margin-bottom: 1rem;
}

ul, ol {
  padding-left: 1.5rem;
}

li {
  margin-bottom: 0.5rem;
}

a {
  color: #0369a1;
}

.callout {
  background: #f0f9ff;
  border-left: 4px solid #0369a1;
  padding: 1.5rem;
  margin: 2rem 0;
  border-radius: 4px;
}

.callout h2 {
  margin-top: 0;
  color: #0369a1;
}

strong {
  font-weight: 700;
}

footer {
  border-top: 1px solid #e5e7eb;
  padding: 2rem 1.5rem;
  text-align: center;
  color: #6b7280;
  font-size: 0.9rem;
  margin-top: 4rem;
}

footer a {
  color: #6b7280;
}

@media (max-width: 640px) {
  nav {
    padding: 1rem;
  }
  nav ul {
    gap: 1rem;
    font-size: 0.875rem;
  }
  main {
    padding: 2rem 1rem;
  }
  .hero h1 {
    font-size: 2rem;
  }
}