:root { color-scheme: light dark; }
body {
  margin: 0 auto; padding: 2.5rem 1.25rem 4rem; max-width: 42rem;
  font: 1rem/1.65 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
h1 { font-size: 1.6rem; line-height: 1.25; margin: 0 0 .25rem; }
h2 { font-size: 1.1rem; margin: 2rem 0 .5rem; }
.sub { margin: 0 0 2rem; opacity: .7; font-size: .95rem; }
footer { margin-top: 3rem; padding-top: 1rem; border-top: 1px solid rgba(128,128,128,.35);
         font-size: .9rem; opacity: .8; }
code { font-size: .9em; }