body {
  font-family: -apple-system, "Segoe UI", Roboto, sans-serif;
  background: #0f1115;
  color: #f2f2f2;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}
main {
  max-width: 560px;
  padding: 2rem;
  text-align: center;
}
h1 {
  font-size: 2.2rem;
  margin-bottom: 0.5rem;
}
button {
  margin-top: 1.5rem;
  padding: 0.6rem 1.2rem;
  font-size: 1rem;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  background: #3b82f6;
  color: white;
}