:root {
  font-family: system-ui, sans-serif;
  color: #171717;
  background: #fff;
  line-height: 1.6;
}
body { margin: 0; }
main { max-width: 36rem; margin: 5rem auto; padding: 0 1.5rem; }
h1 { font-size: 1.75rem; font-weight: 600; line-height: 1.2; }