body {
  margin: 0;
  font-family: system-ui, sans-serif;
  background: #0f172a;
  color: #e5e7eb;
}
header {
  background: #111827;
  padding: 1rem;
  display: flex;
  justify-content: space-between;
}
header a {
  color: #3b82f6;
  margin: 0 10px;
  text-decoration: none;
}
.container { padding: 1rem; }
.card {
  max-width: 400px;
  margin: 2rem auto;
  padding: 1.5rem;
  background: #111827;
  border-radius: 12px;
}
button {
  background: #3b82f6;
  border: none;
  color: white;
  padding: .6rem 1rem;
  border-radius: 8px;
  cursor: pointer;
}
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
}