:root {
  --bg: #07080f;
  --bg2: #0d0f1c;
  --card: #11131f;
  --line: #23263a;
  --text: #e6e8f2;
  --muted: #8b93a7;
  --label: #a6accd;
  --cyan: #8be9fd;
  --violet: #bd93f9;
  --ok: #50fa7b;
  --warn: #f1fa8c;
  --bad: #ff6e6e;
  --eq: #ffb86c;
  --mono: "JetBrains Mono", ui-monospace, Menlo, Consolas, monospace;
  --display: "Space Grotesk", system-ui, sans-serif;
  --body: Inter, system-ui, -apple-system, "Segoe UI", sans-serif;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
body {
  margin: 0;
  background:
    radial-gradient(1200px 600px at 15% -10%, #1d2042 0%, transparent 60%),
    radial-gradient(900px 500px at 100% 0%, #1a1433 0%, transparent 55%),
    var(--bg);
  color: var(--text);
  font: 16px/1.6 var(--body);
}
a { color: var(--cyan); text-decoration: none; }
a:hover { text-decoration: underline; }
code { font-family: var(--mono); font-size: 0.9em; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }

/* nav */
.nav {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 12px max(16px, calc((100% - 1080px) / 2));
  background: rgba(7, 8, 15, 0.82); backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.brand {
  display: inline-flex; align-items: center; gap: 10px; color: var(--text);
  font: 700 21px var(--display); letter-spacing: -0.02em; line-height: 1; white-space: nowrap;
}
.brand:hover { text-decoration: none; filter: brightness(1.08); }
.brand img { width: 38px; height: 38px; flex: none; filter: drop-shadow(0 0 10px rgba(139, 233, 253, 0.35)); }
.brand b {
  background: linear-gradient(90deg, #8be9fd, #a5b4fc 55%, #bd93f9);
  -webkit-background-clip: text; background-clip: text; color: transparent; font-weight: 700;
}
.brand-sub {
  display: inline-flex; align-items: center; height: 22px; padding-left: 10px; margin-left: 2px;
  border-left: 1px solid var(--line); font-weight: 500; color: var(--label);
}
.nav nav { display: flex; gap: 20px; flex-wrap: wrap; font-size: 14px; }
.nav nav a { color: var(--label); }
.nav nav a:hover { color: var(--text); text-decoration: none; }
.nav nav { align-items: center; }
/* The Install button and the GitHub tile: a matched pair of rounded squares, in the site
   nav and the docs bar. */
.install-btn, .gh {
  display: inline-flex; align-items: center; justify-content: center; height: 38px;
  border-radius: 11px; transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}
.install-btn {
  gap: 7px; padding: 0 16px; color: #fff !important; font-weight: 600; letter-spacing: 0.01em;
  background: linear-gradient(135deg, #3d8bfd 0%, #6a6cf6 50%, #9b6bff 100%);
  border: 1px solid rgba(255, 255, 255, 0.16);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.28), 0 8px 22px -8px rgba(122, 92, 255, 0.75);
}
.install-btn:hover {
  text-decoration: none; transform: translateY(-1px);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.32), 0 12px 28px -8px rgba(122, 92, 255, 0.9);
}
.gh {
  width: 38px; color: var(--label);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.07), rgba(255, 255, 255, 0.02));
  border: 1px solid #2c3048; box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.06);
}
.gh svg { width: 20px; height: 20px; }
.gh:hover { color: #fff; border-color: rgba(139, 233, 253, 0.55); transform: translateY(-1px); }
@media (prefers-reduced-motion: reduce) { .install-btn:hover, .gh:hover { transform: none; } }

main, footer { max-width: 1080px; margin: 0 auto; padding: 0 16px; }
section { padding: 72px 0 24px; }
section[id] { scroll-margin-top: 64px; }
h1, h2 { font-family: var(--display); letter-spacing: -0.02em; margin: 0 0 12px; }
h1 { font-size: clamp(40px, 7vw, 72px); line-height: 1.02; }
h2 { font-size: clamp(28px, 4vw, 40px); }
.grad { background: linear-gradient(90deg, var(--cyan), var(--violet)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.sub { color: var(--muted); margin: 0 0 24px; }

/* hero */
.hero { text-align: center; padding-top: 64px; }
.hero-logo { filter: drop-shadow(0 12px 40px rgba(108, 198, 244, 0.25)); margin-bottom: 12px; }
.demo { padding-top: 40px; }
.demo-video {
  display: block; width: 100%; height: auto; aspect-ratio: 16 / 9;
  border-radius: 18px; border: 1px solid var(--line); background: var(--card);
  box-shadow: 0 30px 90px rgba(0, 0, 0, 0.55), 0 0 0 1px rgba(255, 255, 255, 0.03) inset;
}
.lede { max-width: 720px; margin: 20px auto 28px; color: #c8cbe0; font-size: 18px; }
.cta { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.fine { color: var(--muted); font-size: 14px; margin-top: 16px; }
.btn {
  display: inline-block; padding: 12px 22px; border-radius: 10px;
  border: 1px solid var(--line); background: var(--card); color: var(--text);
  font: 600 15px var(--body); cursor: pointer;
}
.btn:hover { border-color: var(--cyan); text-decoration: none; }
.btn.primary { background: linear-gradient(90deg, #2f74d0, #7a5cd6); border-color: transparent; color: #fff; }
.btn.primary:hover { filter: brightness(1.1); }
.btn:disabled { opacity: 0.6; cursor: progress; }

/* ask */
#ask-form { display: flex; gap: 10px; }
#question {
  flex: 1; min-width: 0; padding: 14px 16px; border-radius: 10px;
  border: 1px solid var(--line); background: var(--bg2); color: var(--text);
  font: 16px var(--body);
}
#question:focus { outline: none; border-color: var(--cyan); box-shadow: 0 0 0 3px rgba(139, 233, 253, 0.15); }
.examples { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin: 14px 0; font-size: 14px; color: var(--muted); }
.examples button {
  border: 1px solid var(--line); background: transparent; color: var(--label);
  border-radius: 999px; padding: 6px 12px; font: 13px var(--body); cursor: pointer;
}
.examples button:hover { border-color: var(--violet); color: var(--text); }
.engine { display: flex; align-items: center; gap: 8px; color: var(--muted); font: 13px var(--mono); margin: 4px 0 16px; }
.engine .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--muted); flex: none; }
.engine.booting .dot { background: var(--warn); animation: pulse 1s infinite alternate; }
.engine.ready .dot { background: var(--ok); }
.engine.failed .dot { background: var(--bad); }
@keyframes pulse { to { opacity: 0.3; } }
.preview { margin-top: 20px; padding: 12px 16px; border-left: 3px solid var(--violet); background: rgba(189, 147, 249, 0.06); color: #c8cbe0; font-size: 14px; border-radius: 0 8px 8px 0; }

/* answer card: mirrors the CLI */
.card {
  border: 1px solid var(--line); border-radius: 14px; background: var(--card);
  padding: 22px 24px; font-family: var(--mono); font-size: 14px;
  animation: rise 0.25s ease-out;
}
@keyframes rise { from { opacity: 0; transform: translateY(6px); } }
.card.answered { border-color: rgba(80, 250, 123, 0.5); }
.card.degraded { border-color: rgba(241, 250, 140, 0.5); }
.card.refused { border-color: rgba(255, 110, 110, 0.5); }
.card-head { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.badge { padding: 2px 10px; border-radius: 6px; font-weight: 600; color: #1e1f29; letter-spacing: 0.04em; }
.answered .badge { background: var(--ok); }
.degraded .badge { background: var(--warn); }
.refused .badge { background: var(--bad); }
.category { color: var(--muted); }
.question { color: var(--muted); margin: 10px 0 0; font-family: var(--body); }
.big { margin: 18px 0 6px; color: #fff; font: 700 clamp(32px, 6vw, 48px) var(--display); }
.big .unit { color: var(--cyan); font-weight: 500; margin-left: 10px; }
.rows { display: grid; grid-template-columns: max-content 1fr; gap: 10px 18px; margin-top: 18px; }
.rows dt { color: var(--label); font-weight: 600; text-align: right; }
.rows dd { margin: 0; min-width: 0; overflow-wrap: anywhere; }
.meter { display: inline-flex; gap: 2px; vertical-align: middle; margin-right: 10px; }
.meter i { width: 8px; height: 10px; border-radius: 2px; background: var(--line); }
.meter.ok i.on { background: var(--ok); }
.meter.warn i.on { background: var(--warn); }
.meter.bad i.on { background: var(--bad); }
.conf-high { color: var(--ok); }
.conf-medium { color: var(--warn); }
.conf-low { color: var(--bad); }
.eq-id { color: var(--violet); }
.eq-name { color: var(--muted); margin-left: 8px; }
.eq-math { display: block; color: var(--eq); font-size: 17px; margin: 4px 0 2px 2px; }
.eq-src { display: block; color: var(--muted); font-size: 12px; }
.input-row .sym { color: var(--muted); }
.origin-given { color: var(--text); font-weight: 600; }
.origin-constant { color: var(--violet); }
.origin-assumption { color: var(--warn); }
.input-row .tag { color: var(--muted); margin-left: 8px; }
.rows ul { margin: 0; padding-left: 18px; }
.caveats { color: var(--muted); }
.redirect { border: 1px solid var(--violet); color: var(--violet); background: transparent; border-radius: 8px; padding: 6px 10px; font: 13px var(--mono); cursor: pointer; text-align: left; }
.redirect:hover { background: rgba(189, 147, 249, 0.1); }
.error { color: var(--bad); font-family: var(--mono); }

/* how */
.stages { list-style: none; counter-reset: s; display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 12px; padding: 0; margin: 0; }
.stages li { counter-increment: s; background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 16px; }
.stages li::before { content: counter(s); display: inline-grid; place-items: center; width: 26px; height: 26px; border-radius: 50%; background: linear-gradient(135deg, #2f74d0, #7a5cd6); font: 700 13px var(--mono); margin-bottom: 8px; }
.stages b { display: block; font-family: var(--display); font-size: 17px; }
.stages span { color: var(--muted); font-size: 14px; }

/* models */
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(220px, 40vw), 1fr)); gap: 16px; }
.grid figure { margin: 0; background: var(--card); border: 1px solid var(--line); border-radius: 14px; overflow: hidden; }
.grid img { display: block; width: 100%; aspect-ratio: 1; object-fit: cover; }
.grid figcaption { padding: 10px 14px 14px; color: var(--muted); font-size: 14px; }
.grid figcaption b { color: var(--text); font-family: var(--mono); }

/* install */
.cmd { display: grid; grid-template-columns: 120px 1fr auto; align-items: center; gap: 12px; background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 10px 12px; margin-bottom: 10px; }
.cmd span { color: var(--muted); font-size: 13px; }
.cmd code { overflow-x: auto; white-space: nowrap; color: var(--text); }
.copy { border: 1px solid var(--line); background: transparent; color: var(--label); border-radius: 8px; padding: 6px 10px; cursor: pointer; font: 13px var(--body); }
.copy:hover { border-color: var(--cyan); color: var(--text); }

footer { border-top: 1px solid var(--line); margin-top: 72px; padding: 24px 16px 48px; color: var(--muted); font-size: 14px; }
footer .credits { font-size: 12px; }

/* Phones: every link stays in the nav, as a row under the logo that scrolls sideways. */
@media (max-width: 640px) {
  .nav { flex-wrap: wrap; row-gap: 4px; padding-bottom: 4px; }
  .nav nav {
    width: 100%; flex-wrap: nowrap; gap: 14px; font-size: 13px;
    overflow-x: auto; scrollbar-width: none; -webkit-overflow-scrolling: touch;
  }
  .nav nav::-webkit-scrollbar { display: none; }
  .nav nav a { white-space: nowrap; padding: 6px 0; }
  /* Install and GitHub become two square tiles beside the logo, so neither scrolls away. */
  .nav nav a.install-btn, .nav nav a.gh { position: absolute; top: 12px; width: 38px; padding: 0; }
  .nav nav a.install-btn { right: 62px; }
  .nav nav a.gh { right: 16px; }
  .nav nav a.install-btn .label { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
  .nav nav a.install-btn svg { width: 19px; height: 19px; }
  section { padding-top: 48px; }
  section[id] { scroll-margin-top: 100px; }
  .hero { padding-top: 40px; }
  .brand { font-size: 19px; }
  .brand img { width: 32px; height: 32px; }
  .lede { font-size: 17px; }
  #ask-form { flex-direction: column; }
  .examples button { text-align: left; }
  .card { padding: 16px; }
  .rows { grid-template-columns: 1fr; gap: 4px; }
  .rows dt { text-align: left; margin-top: 8px; }
  .grid { gap: 10px; }
  .grid figcaption { padding: 8px 10px 10px; font-size: 13px; }
  .cmd { grid-template-columns: 1fr auto; }
  .cmd span { grid-column: 1 / -1; }
  /* The whole command, wrapped, rather than a strip to scroll. */
  .cmd code { white-space: normal; overflow-wrap: anywhere; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .card, .engine.booting .dot { animation: none; }
}