html, body {
  height: 100%;
  margin: 0;
}
body {
  display: flex;
  align-items: center;
  justify-content: center;
  background: #111;
  color: #eee;
  font-family: system-ui, sans-serif;
}
div {
  text-align: center;
  padding: 2rem 3rem;
  border: 1px solid #333;
  border-radius: 8px;
}