:root {
  color-scheme: dark;
  --bg: #050d18;
  --surface: #0d1825;
  --surface-2: #131f2e;
  --text: #f7f9fc;
  --muted: #9aa5b4;
  --line: rgba(255, 255, 255, 0.1);
  --accent: #6872ff;
  --accent-soft: rgba(104, 114, 255, 0.14);
  --max: 760px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(circle at 82% 4%, rgba(104, 114, 255, 0.16), transparent 28rem),
    var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  font-size: 17px;
  line-height: 1.65;
}

a { color: #aeb4ff; }
a:hover { color: #d5d8ff; }

.shell {
  width: min(calc(100% - 40px), var(--max));
  margin: 0 auto;
}

header {
  border-bottom: 1px solid var(--line);
  background: rgba(5, 13, 24, 0.86);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.nav {
  min-height: 70px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: var(--text);
  text-decoration: none;
  font-size: 19px;
  font-weight: 700;
  letter-spacing: 0.01em;
}

.mark {
  width: 34px;
  height: 34px;
  border-radius: 11px;
  display: grid;
  place-items: center;
  background: var(--accent);
  font-size: 20px;
}

.nav-links { display: flex; gap: 18px; }
.nav-links a { color: var(--muted); text-decoration: none; font-size: 14px; }

main { padding: 72px 0 88px; }

.eyebrow {
  color: #9ea5ff;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1, h2 {
  font-family: ui-rounded, "SF Pro Rounded", -apple-system, BlinkMacSystemFont, sans-serif;
  letter-spacing: -0.025em;
  line-height: 1.12;
}

h1 { margin: 14px 0 18px; font-size: clamp(40px, 8vw, 64px); }
h2 { margin: 48px 0 14px; font-size: 27px; }
h3 { margin: 28px 0 8px; font-size: 19px; }

.lede { color: #bdc5d0; font-size: 21px; line-height: 1.55; }
.updated { margin-top: 24px; color: var(--muted); font-size: 14px; }

.card-grid {
  margin-top: 38px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.card {
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: linear-gradient(150deg, var(--surface-2), var(--surface));
}

.card strong { display: block; margin-bottom: 8px; font-size: 19px; }
.card p { margin: 0; color: var(--muted); }

.cta {
  display: inline-flex;
  margin-top: 28px;
  padding: 13px 18px;
  border-radius: 13px;
  background: var(--accent);
  color: white;
  text-decoration: none;
  font-weight: 700;
}

.cta:hover { color: white; background: #7c84ff; }

.toc {
  margin: 36px 0 8px;
  padding: 20px 24px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--accent-soft);
}

.toc strong { display: block; margin-bottom: 7px; }
.toc a { margin-right: 14px; font-size: 15px; }

section { scroll-margin-top: 24px; }
ul { padding-left: 22px; }
li + li { margin-top: 8px; }
p, li { color: #c4cbd5; }

.notice {
  padding: 18px 20px;
  border-left: 3px solid var(--accent);
  border-radius: 0 14px 14px 0;
  background: var(--accent-soft);
}

footer {
  padding: 26px 0 42px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 14px;
}

footer .shell { display: flex; justify-content: space-between; gap: 18px; }
footer a { color: var(--muted); }

@media (max-width: 620px) {
  body { font-size: 16px; }
  .shell { width: min(calc(100% - 28px), var(--max)); }
  .nav { align-items: flex-start; padding: 16px 0; }
  .nav-links { gap: 11px; flex-wrap: wrap; justify-content: flex-end; }
  main { padding: 54px 0 68px; }
  .lede { font-size: 19px; }
  .card-grid { grid-template-columns: 1fr; }
  footer .shell { flex-direction: column; }
}