body {
  background-color: #121212;
  color: #e0e0e0;
  font-family: sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}
.card {
  background: #1e1e1e;
  padding: 24px;
  border-radius: 8px;
  border: 1px solid #333;
  text-align: center;
}
button {
  background: #2ecc71;
  color: #fff;
  border: none;
  padding: 10px 16px;
  border-radius: 4px;
  font-weight: bold;
  cursor: pointer;
}