:root {
  --bg: #f5f7fb;
  --surface: #ffffff;
  --text: #2a2f45;
  --accent: #3b82f6;
  --muted: #5c6a91;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

.site-header {
  padding: 3rem 1.5rem;
  background: linear-gradient(135deg, #4f46e5 0%, #2563eb 100%);
  color: white;
  text-align: center;
}

.site-header h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(2rem, 4vw, 3rem);
}

.site-nav {
  display: flex;
  justify-content: center;
  gap: 1rem;
  padding: 1rem 0;
  background: #ffffff;
  border-bottom: 1px solid #e5e7eb;
}

.site-nav a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
}

.site-nav a:hover {
  text-decoration: underline;
}

main {
  max-width: 900px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

.content-section {
  margin-bottom: 2rem;
  padding: 1.75rem;
  background: var(--surface);
  border-radius: 1rem;
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
}

.content-section h2 {
  margin-top: 0;
}

.content-section ul {
  padding-left: 1.25rem;
}

.content-section li {
  margin-bottom: 0.75rem;
}

.site-footer {
  padding: 1.5rem;
  text-align: center;
  color: var(--muted);
}

@media (max-width: 640px) {
  .site-nav {
    flex-direction: column;
    gap: 0.5rem;
  }
}