:root {
  color-scheme: light;
  --bg: #f3f6fa;
  --surface: #ffffff;
  --text: #17263c;
  --muted: #52627a;
  --accent: #245ac4;
  --border: #d4deeb;
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #101827;
  --surface: #1a2638;
  --text: #edf3fc;
  --muted: #b2c1d8;
  --accent: #9bbcff;
  --border: #394b64;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, sans-serif;
  line-height: 1.65;
}
.container { width: min(900px, 90%); margin-inline: auto; }
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding-block: 1.5rem;
  border-bottom: 1px solid var(--border);
}
nav { display: flex; flex-wrap: wrap; align-items: center; gap: 1rem; }
a { color: var(--accent); text-underline-offset: 0.25em; }
.brand { font-size: 1.6rem; font-weight: 800; text-decoration: none; }
nav a[aria-current="page"] { font-weight: 700; }
button, .button {
  display: inline-block;
  padding: 0.65rem 1rem;
  border: 1px solid var(--accent);
  border-radius: 0.6rem;
  background: var(--surface);
  color: var(--accent);
  font: inherit;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
}
[hidden] { display: none !important; }
button:hover, .button:hover { background: var(--bg); }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 4px; }
main { flex: 1; padding-block: 2rem 3rem; }
.hero { padding-block: 3rem; }
.intro { padding-block: 1.5rem; }
h1 { font-size: clamp(2rem, 6vw, 3.4rem); line-height: 1.15; margin: 0.5rem 0 1rem; }
h2 { font-size: 1.35rem; line-height: 1.3; }
p, li { overflow-wrap: anywhere; }
.lead { color: var(--muted); font-size: 1.15rem; max-width: 650px; }
.eyebrow { color: var(--accent); font-weight: 700; font-size: 0.85rem; }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: 1rem; padding: 1.75rem; }
.tags { display: flex; flex-wrap: wrap; gap: 0.5rem; list-style: none; padding: 0; margin-block: 1.25rem; }
.tags li { background: var(--bg); border: 1px solid var(--border); border-radius: 2rem; padding: 0.25rem 0.75rem; font-size: 0.85rem; }
.back { display: inline-block; margin-bottom: 0.5rem; }
pre { overflow-x: auto; background: var(--bg); border: 1px solid var(--border); border-radius: 0.5rem; padding: 1rem; }
code { font-family: ui-monospace, monospace; }
footer { padding-block: 1.5rem; border-top: 1px solid var(--border); color: var(--muted); font-size: 0.85rem; }
.skip-link { position: absolute; top: -100px; left: 1rem; padding: 0.5rem 1rem; background: var(--surface); z-index: 1; }
.skip-link:focus { top: 1rem; }
@media (max-width: 540px) {
  header { align-items: flex-start; flex-direction: column; }
  .hero { padding-block: 1.5rem; }
  .card { padding: 1.25rem; }
}