body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 16px;
  box-sizing: border-box;
  font: 14px/1.6 system-ui, -apple-system, "PingFang SC", sans-serif;
  color: #1f2329;
  background: #f5f6f7;
}
main { max-width: 480px; text-align: center; }
h1 { font-size: 20px; margin: 0 0 8px; }
p { margin: 0; color: #646a73; }