* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
  background: #000;
  color: #fff;
  min-height: 100vh;
  display: grid;
  place-items: center;
}
main { text-align: center; padding: 2rem; }
h1 { font-size: 2rem; }
a {
  color: #fff;
  text-decoration: none;
  border: 1px solid #555;
  border-radius: 8px;
  padding: 0.5rem 1rem;
  display: inline-block;
  margin: 0.5rem;
}
a:hover { border-color: #fff; }