body {
  margin: 0;
  padding: 72px 16px 48px;
  background: #fff;
  color: #111;
  font: 16px/1.5 system-ui, sans-serif;
  text-align: center;
}
main { max-width: 640px; margin: 0 auto; }
h1 { font-size: 1.75rem; margin: 0 0 .5em; }
h2 { font-size: 1rem; margin: 2em 0 .25em; }
p { margin: 0 0 1em; }
a { color: inherit; }

/* Desktop: centre the page vertically */
@media (min-width: 700px) {
  body { min-height: 100vh; box-sizing: border-box; display: grid; place-items: center; padding: 48px 16px; }
}