:root {
  color-scheme: dark;
  --bg: #07111f;
  --panel: rgba(16, 31, 52, 0.78);
  --panel-strong: #102541;
  --line: rgba(173, 205, 238, 0.16);
  --text: #eaf3ff;
  --muted: #9eb3ca;
  --accent: #72b7ff;
  --accent-strong: #a7d3ff;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 12% 0%, rgba(58, 126, 205, .26), transparent 35rem),
    radial-gradient(circle at 90% 10%, rgba(92, 83, 196, .18), transparent 32rem),
    var(--bg);
  color: var(--text);
  font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", sans-serif;
  line-height: 1.75;
}

a { color: var(--accent-strong); }
.shell { width: min(1080px, calc(100% - 40px)); margin: 0 auto; }
.site-header { padding: 24px 0; border-bottom: 1px solid var(--line); }
.header-row { display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.brand { color: var(--text); font-weight: 800; letter-spacing: .12em; text-decoration: none; }
.back-link { color: var(--muted); text-decoration: none; font-size: .92rem; }
.back-link:hover { color: var(--text); }
.language-toggle {
  border: 1px solid rgba(114, 183, 255, .48);
  border-radius: 999px;
  background: rgba(114, 183, 255, .12);
  color: var(--accent-strong);
  padding: 8px 15px;
  font: inherit;
  cursor: pointer;
}
.language-toggle:hover { background: rgba(114, 183, 255, .22); }
.hero { padding: 72px 0 42px; }
.eyebrow { color: var(--accent); font-size: .82rem; font-weight: 700; letter-spacing: .16em; text-transform: uppercase; }
h1 { max-width: 800px; margin: 12px 0 18px; font-size: clamp(2.2rem, 6vw, 4.6rem); line-height: 1.08; letter-spacing: -.04em; }
.hero p { max-width: 720px; margin: 0; color: var(--muted); font-size: 1.08rem; }
.notice { margin: 28px 0 44px; padding: 16px 20px; border: 1px solid var(--line); border-radius: 16px; background: rgba(255,255,255,.035); color: var(--muted); font-size: .92rem; }
.document { max-width: 850px; padding: 42px 46px; margin: 0 0 80px; border: 1px solid var(--line); border-radius: 24px; background: var(--panel); box-shadow: 0 24px 80px rgba(0,0,0,.2); }
.document h1 { display: none; }
.document h2 { margin: 2.2em 0 .45em; padding-top: .4em; border-top: 1px solid var(--line); font-size: 1.55rem; line-height: 1.3; }
.document h3 { margin: 1.7em 0 .35em; color: var(--accent-strong); font-size: 1.12rem; line-height: 1.4; }
.document p { margin: .9em 0; }
.document ul, .document ol { padding-left: 1.45em; }
.document li { margin: .4em 0; }
.document strong { color: var(--accent-strong); }
.document code { padding: .15em .35em; border-radius: 5px; background: rgba(255,255,255,.1); }
.document a { overflow-wrap: anywhere; }
.lang-section[hidden] { display: none; }
.loading, .error { color: var(--muted); }
.error { color: #ffb4b4; }
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin: 42px 0 80px; }
.card { display: flex; flex-direction: column; padding: 25px; border: 1px solid var(--line); border-radius: 20px; background: var(--panel); }
.card h2 { margin: 0 0 7px; font-size: 1.2rem; }
.card p { margin: 0 0 18px; color: var(--muted); font-size: .94rem; }
.card-links { display: flex; flex-wrap: wrap; gap: 9px; margin-top: auto; }
.card-links a { padding: 7px 11px; border-radius: 999px; background: rgba(114,183,255,.12); color: var(--accent-strong); text-decoration: none; font-size: .85rem; }
.card-links a:hover { background: rgba(114,183,255,.24); }
footer { padding: 28px 0 44px; border-top: 1px solid var(--line); color: var(--muted); font-size: .85rem; }
@media (max-width: 760px) {
  .shell { width: min(100% - 28px, 680px); }
  .header-row { flex-wrap: wrap; }
  .back-link { order: 3; width: 100%; }
  .hero { padding: 48px 0 30px; }
  .document { padding: 26px 22px; border-radius: 18px; }
  .cards { grid-template-columns: 1fr; }
}