body {
  font-family: system-ui, sans-serif;
  margin: 0;
  background: #f9fafb;
  color: #222;
}

header {
  background: #15f36a7c;
  color: #222;
  padding: 1.5rem;
}

.category-nav ul {
  list-style: none;
  padding: 0;
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.category-nav a {
  display: block;
  padding: 1rem;
  background: white;
  border-radius: 10px;
  text-decoration: none;
  color: #004aad;
  font-weight: bold;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  transition: transform 0.1s ease-in-out;
}

.category-nav a:hover {
  transform: scale(1.02);
}

section {
  background: white;
  margin: 1rem;
  padding: 1rem 1.5rem;
  border-left: 4px solid #004aad;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

pre {
  background: #f0f0f0;
  padding: 0.5rem;
  border-radius: 6px;
  overflow-x: auto;
}