body {
  font-family: system-ui, sans-serif;
  text-align: center;
  padding: 100px;
  background: #0f0f0f;
  color: #fff;
}
h1 { font-size: 3rem; }
button {
  padding: 15px 30px;
  font-size: 1.2rem;
  background: #00ff88;
  color: black;
  border: none;
  border-radius: 50px;
  cursor: pointer;
}