body {
  font-family: system-ui, sans-serif;
  margin: 0;
  background: #f5f5f5;
  color: #222;
}

header {
  background: #222;
  color: #fff;
  padding: 1rem;
}

header h1 {
  margin: 0 0 0.5rem;
}

nav a {
  color: #fff;
  margin-right: 1rem;
  text-decoration: none;
}

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

main {
  max-width: 900px;
  margin: 2rem auto;
  padding: 0 1rem;
}

section {
  background: #fff;
  padding: 1.5rem;
  margin-bottom: 1rem;
  border-radius: 6px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.08);
}

.key-category {
  background: #fafafa;
  padding: 1rem;
  margin-bottom: 1rem;
  border-left: 4px solid #222;
}

footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.9rem;
  color: #666;
}