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

:root {
  --color-bg: #ffffff;
  --color-text: #1a1a1a;
  --color-muted: #666666;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-border: #e5e7eb;
  --max-width: 960px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
}

a { color: var(--color-accent); text-decoration: none; }
a:hover { color: var(--color-accent-hover); text-decoration: underline; }

/* Header / Nav */
header {
  border-bottom: 1px solid var(--color-border);
  padding: 1rem 2rem;
}

nav {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

nav .site-name {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
}

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

/* Main content */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 3rem 2rem;
}

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

.hero h1 {
  font-size: 2.5rem;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.hero p {
  font-size: 1.125rem;
  color: var(--color-muted);
  max-width: 600px;
  margin: 0 auto 2rem;
}

.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  background: var(--color-accent);
  color: #fff;
  border-radius: 6px;
  font-weight: 600;
}

.btn:hover {
  background: var(--color-accent-hover);
  text-decoration: none;
  color: #fff;
}

section { margin-bottom: 3rem; }
section h2 { font-size: 1.5rem; margin-bottom: 1rem; }
section p { color: var(--color-muted); }

/* Footer */
footer {
  border-top: 1px solid var(--color-border);
  padding: 2rem;
  text-align: center;
  color: var(--color-muted);
  font-size: 0.875rem;
}

/* Responsive */
@media (max-width: 640px) {
  .hero h1 { font-size: 1.75rem; }
  nav { flex-direction: column; gap: 0.5rem; }
}