:root {
  color-scheme: light dark;
  --accent: #0878f9;
  --accent-soft: color-mix(in srgb, var(--accent) 12%, transparent);
  --background: #f5f7fa;
  --surface: #ffffff;
  --text: #12151a;
  --secondary: #5c6570;
  --border: #dce1e8;
  --shadow: 0 16px 45px rgb(15 35 65 / 10%);
}

@media (prefers-color-scheme: dark) {
  :root {
    --accent: #4da3ff;
    --background: #0d1117;
    --surface: #161b22;
    --text: #f2f5f8;
    --secondary: #aeb7c2;
    --border: #303844;
    --shadow: 0 18px 50px rgb(0 0 0 / 28%);
  }
}

* { box-sizing: border-box; }

html { font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", system-ui, sans-serif; }

body {
  margin: 0;
  background:
    radial-gradient(circle at 15% 0%, var(--accent-soft), transparent 32rem),
    var(--background);
  color: var(--text);
  line-height: 1.62;
}

a { color: var(--accent); }

.shell {
  width: min(100% - 2rem, 780px);
  margin: 0 auto;
}

header {
  padding: 2rem 0 1.25rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: .75rem;
  color: var(--text);
  font-size: 1.05rem;
  font-weight: 700;
  text-decoration: none;
}

.mark {
  display: grid;
  width: 2.4rem;
  height: 2.4rem;
  place-items: center;
  border-radius: .7rem;
  background: var(--accent);
  color: white;
  font-size: 1.25rem;
}

main { padding: 1rem 0 4rem; }

.hero {
  padding: clamp(2rem, 7vw, 4.5rem) 0 2.5rem;
}

h1, h2, h3 { line-height: 1.18; letter-spacing: -.025em; }
h1 { margin: 0 0 1rem; font-size: clamp(2.25rem, 7vw, 4.5rem); }
h2 { margin-top: 2.25rem; font-size: 1.45rem; }
h3 { margin-top: 1.6rem; font-size: 1.08rem; }
p, li { font-size: 1rem; }
.lede { max-width: 44rem; color: var(--secondary); font-size: 1.2rem; }
.meta { color: var(--secondary); font-size: .9rem; }

.grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

.card, .document {
  border: 1px solid var(--border);
  border-radius: 1.25rem;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.card {
  display: block;
  padding: 1.4rem;
  color: var(--text);
  text-decoration: none;
}

.card:hover { border-color: var(--accent); transform: translateY(-1px); }
.card h2 { margin: 0 0 .4rem; }
.card p { margin: 0; color: var(--secondary); }

.document { padding: clamp(1.4rem, 5vw, 3rem); }
.document h1 { font-size: clamp(2rem, 6vw, 3.35rem); }
.document ul, .document ol { padding-left: 1.25rem; }
.document strong { font-weight: 700; }

.notice {
  margin: 1.5rem 0;
  padding: 1rem 1.1rem;
  border-left: 4px solid var(--accent);
  border-radius: .55rem;
  background: var(--accent-soft);
}

footer {
  padding: 1.5rem 0 2.5rem;
  border-top: 1px solid var(--border);
  color: var(--secondary);
  font-size: .9rem;
}

.footer-links { display: flex; flex-wrap: wrap; gap: 1rem; }

@media (max-width: 620px) {
  .grid { grid-template-columns: 1fr; }
  .shell { width: min(100% - 1.25rem, 780px); }
  header { padding-top: 1.25rem; }
}

@media (prefers-reduced-motion: no-preference) {
  .card { transition: transform 160ms ease, border-color 160ms ease; }
}