:root {
  color-scheme: light dark;
  --text: #1f2328;
  --muted: #57606a;
  --background: #ffffff;
  --link: #0a76a7;
  --rule: #d0d7de;
}

@media (prefers-color-scheme: dark) {
  :root {
    --text: #e6edf3;
    --muted: #9da7b1;
    --background: #121619;
    --link: #6cc3ee;
    --rule: #30363d;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0 auto;
  max-width: 42rem;
  padding: 2rem 1rem 3rem;
  font: 1.0625rem/1.6 system-ui, -apple-system, "Segoe UI", Roboto, Ubuntu, sans-serif;
  color: var(--text);
  background: var(--background);
}

header { text-align: center; }
h1 { margin: 0 0 1.5rem; }
img { max-width: 100%; height: auto; }

h2 { margin: 2rem 0 0.5rem; font-size: 1.25rem; }
ul { padding-left: 1.25rem; }
li { margin: 0.4rem 0; }
.lead { font-size: 1.125rem; }

a { color: var(--link); text-underline-offset: 0.15em; }
a:focus-visible { outline: 2px solid var(--link); outline-offset: 2px; border-radius: 2px; }

footer {
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid var(--rule);
  font-size: 0.9rem;
  color: var(--muted);
}
footer p { margin: 0.4rem 0; }