/* Header and navigation */
header {
  background: #f8f8f8;
  padding: 1rem;
  border-bottom: 1px solid #ddd;
}

.main-menu {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  gap: 1rem;
}

.main-menu li a {
  text-decoration: none;
  color: #333;
  font-weight: bold;
}

.main-menu li a.active {
  color: #0066cc;
  border-bottom: 2px solid #0066cc;
}

/* Responsive menu */
@media (max-width: 600px) {
  .main-menu {
    flex-direction: column;
    gap: 0.5rem;
  }
}