:root {
  color-scheme: light dark;
  --bg: #f6f7f9;
  --surface: #ffffff;
  --ink: #1b2430;
  --muted: #5a6675;
  --rule: #d9dee5;
  --accent: #1f5eff;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121519;
    --surface: #1a1f26;
    --ink: #e8ebef;
    --muted: #9aa5b3;
    --rule: #2c343e;
    --accent: #7fa4ff;
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; background: var(--bg); color: var(--ink); }
body { font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; }
a { color: var(--accent); }
code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: .95em; }
.skip { position: absolute; left: -999px; top: 0; padding: .5rem 1rem; background: var(--surface); }
.skip:focus { left: .5rem; }
.layout { display: flex; flex-direction: column; min-height: 100vh; }
nav { background: var(--surface); border-bottom: 1px solid var(--rule); padding: 1rem 1.25rem; }
nav .brand { font-weight: 700; margin: 0 0 .75rem; font-size: 1.1rem; }
nav h2 { font-size: .8rem; letter-spacing: .06em; text-transform: uppercase; color: var(--muted); margin: 1rem 0 .25rem; }
nav ul { list-style: none; margin: 0; padding: 0; }
nav li a { display: block; min-height: 44px; padding: .6rem .5rem; margin: 0 -.5rem; border-radius: 6px; text-decoration: none; color: var(--ink); }
nav li a:hover, nav li a:focus { background: var(--bg); text-decoration: underline; }
main { padding: 1.5rem 1.25rem 3rem; max-width: 40rem; }
main h1 { font-size: 1.5rem; margin: 0 0 .75rem; }
.muted { color: var(--muted); }
@media (min-width: 720px) {
  .layout { flex-direction: row; }
  nav { width: 240px; flex: none; border-bottom: 0; border-right: 1px solid var(--rule); min-height: 100vh; position: sticky; top: 0; }
  main { padding: 2.5rem 3rem; }
}