/* torchmodal landing page. One accent colour, system fonts, light code blocks. */
:root {
  --bg: #ffffff; --bg-2: #f5f6f8; --paper: #ffffff;
  --ink: #1b1f2a; --ink-2: #3d4350; --muted: #6b7180;
  --line: #e2e4e9; --line-2: #c9cdd6;
  --accent: #1f3fb0; --accent-bg: #eef1fb;
  --ok: #1d7a4f; --bad: #b3261e;
  --maxw: 900px; --wide: 1080px; --rad: 6px;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg); color: var(--ink); font-family: var(--sans);
  font-size: 17px; line-height: 1.6; -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--ink); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
code { font-family: var(--mono); font-size: 0.9em; background: var(--bg-2); border: 1px solid var(--line); border-radius: 4px; padding: 0 4px; }
pre code { background: none; border: 0; padding: 0; font-size: inherit; }
cite { font-style: italic; }
.skip { position: absolute; left: -9999px; top: 0; background: var(--ink); color: #fff; padding: 8px 12px; z-index: 20; }
.skip:focus { left: 12px; top: 12px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* header */
.top { border-bottom: 1px solid var(--line); }
.top-in { max-width: var(--wide); margin: 0 auto; padding: 14px 24px; display: flex; align-items: center; gap: 24px; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 9px; color: var(--ink); text-decoration: none; }
.brand svg { display: block; }
.brand-name { font-size: 17px; font-weight: 600; }
nav { display: flex; gap: 18px; font-size: 15px; margin-left: auto; flex-wrap: wrap; }
nav a { color: var(--ink-2); text-decoration: none; }
nav a:hover { color: var(--accent); text-decoration: underline; }

/* page */
.page { max-width: var(--wide); margin: 0 auto; padding: 0 24px 48px; }
section { margin: 0 0 72px; scroll-margin-top: 16px; }
section > h2, section > p, section > .note, .features, .faq details, .papers, .bib, .usecase { max-width: var(--maxw); }
h2 { font-size: 24px; font-weight: 600; line-height: 1.25; margin: 0 0 14px; letter-spacing: -0.01em; }
h3 { font-size: 16px; font-weight: 600; margin: 0 0 6px; }
p { margin: 0 0 16px; }
.note { font-size: 15px; color: var(--ink-2); margin-top: 16px; }

/* intro */
.intro { padding-top: 52px; }
h1 { font-size: 36px; font-weight: 600; line-height: 1.2; letter-spacing: -0.015em; margin: 0 0 18px; max-width: var(--maxw); }
.lede { font-size: 18px; line-height: 1.6; max-width: 70ch; margin: 0 0 24px; }
.install { display: flex; align-items: center; gap: 10px; margin: 0 0 12px; flex-wrap: wrap; }
.cmd { margin: 0; padding: 8px 14px; font-size: 15px; display: inline-block; }
.copy { font: 13px var(--sans); border: 1px solid var(--line-2); border-radius: var(--rad); padding: 6px 10px; background: var(--paper); color: var(--ink-2); cursor: pointer; }
.copy:hover { border-color: var(--ink); color: var(--ink); }
.facts { font-size: 15px; color: var(--ink-2); margin: 0 0 56px; }

/* code blocks */
pre { background: var(--bg-2); border: 1px solid var(--line); border-radius: var(--rad); padding: 16px 18px; margin: 0;
  font-family: var(--mono); font-size: 13.5px; line-height: 1.6; color: var(--ink); overflow-x: auto; }
pre .kw { color: #7a2e8c; } pre .co { color: var(--muted); } pre .st { color: #0b6e4f; }
.bib { margin-top: 12px; }

/* the recorded run */
.stage {
  display: grid; grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr);
  background: var(--paper); border: 1px solid var(--line-2); border-radius: var(--rad); overflow: hidden; margin: 8px 0 0;
  --g-knows: #1f3fb0; --g-guess: #b4b9c6; --g-wrong: #b3261e; --g-wrong-bg: rgba(179, 38, 30, .08); --g-ok: #1d7a4f; --g-und: #9aa0ad;
  --g-node: #ffffff; --g-self: #1b1f2a; --g-label: #1b1f2a; --g-halo: rgba(255, 255, 255, .92); --g-track: #e2e4e9; --g-glow: 0;
}
.stage-graph { position: relative; min-height: 460px; }
.stage-graph canvas { position: absolute; inset: 0; width: 100%; height: 100%; display: block; }
.stage-legend { position: absolute; left: 14px; bottom: 10px; display: flex; flex-wrap: wrap; gap: 4px 14px;
  font-family: var(--mono); font-size: 11px; color: var(--muted); }
.stage-legend span { display: inline-flex; align-items: center; gap: 6px; }
.stage-legend .ln { width: 16px; height: 3px; display: inline-block; }
.stage-legend .ln.knows { background: var(--g-knows); }
.stage-legend .ln.guess { background: var(--g-guess); }
.stage-legend .ln.wrong { background: var(--g-wrong); }
.stage-legend .dm { width: 8px; height: 8px; background: var(--g-self); transform: rotate(45deg); display: inline-block; }
.stage-side { padding: 20px 22px; border-left: 1px solid var(--line); display: flex; flex-direction: column; gap: 14px; background: var(--bg-2); }
.stage-side .ep { font-family: var(--mono); font-size: 13px; color: var(--ink-2); }
.stage-side .ep b[data-truth="1"] { color: var(--ok); } .stage-side .ep b[data-truth="0"] { color: var(--bad); }
.stats { margin: 0; display: grid; gap: 8px; }
.stats div { display: grid; grid-template-columns: 1fr; border-top: 1px solid var(--line); padding-top: 8px; }
.stats dt { font-size: 13px; color: var(--muted); }
.stats dd { margin: 0; font-size: 18px; font-weight: 600; font-variant-numeric: tabular-nums; }
.stats dd small { font-size: 13px; font-weight: 400; color: var(--muted); }
.scrubrow { display: flex; gap: 10px; align-items: center; }
.scrubrow input[type=range] { accent-color: var(--accent); }
.stage-side .done { font-size: 14px; color: var(--ink-2); margin: 0; }

/* feature list */
.features { margin: 0; display: grid; grid-template-columns: 1fr 1fr; gap: 18px 36px; }
.features dt { font-weight: 600; margin-bottom: 4px; }
.features dd { margin: 0; font-size: 15.5px; color: var(--ink-2); }

/* playground */
.play { border: 1px solid var(--line-2); border-radius: var(--rad); padding: 22px; display: grid; grid-template-columns: minmax(0, 320px) minmax(0, 1fr); gap: 32px; }
.hint { font-size: 14px; color: var(--muted); margin: 0 0 12px; }
.matrix { border-collapse: collapse; font-family: var(--mono); font-size: 12px; margin-bottom: 18px; }
.matrix th { font-weight: 500; color: var(--muted); padding: 3px 6px; }
.matrix td { padding: 2px; }
.cellbtn { width: 38px; height: 30px; border: 1px solid var(--line-2); border-radius: 4px; background: var(--paper);
  color: var(--muted); font-family: var(--mono); font-size: 12px; cursor: pointer; }
.cellbtn[data-on="1"] { background: var(--accent); color: #fff; border-color: var(--accent); }
.cellbtn:hover { border-color: var(--ink); }
.ctl { margin-bottom: 14px; }
.ctl label { display: flex; justify-content: space-between; align-items: baseline; font-family: var(--mono); font-size: 12px; margin-bottom: 6px; }
.ctl label b { font-weight: 500; color: var(--muted); }
.ctl output { font-variant-numeric: tabular-nums; }
input[type=range] { width: 100%; accent-color: var(--accent); margin: 0; }
.worldrow { display: grid; grid-template-columns: 28px 1fr; gap: 10px; align-items: center; margin-bottom: 10px; }
.worldrow .wname { font-family: var(--mono); font-size: 12px; color: var(--muted); }
.tabs { display: flex; gap: 0; margin-bottom: 16px; }
.tab { font-family: var(--mono); font-size: 13px; padding: 6px 12px; border: 1px solid var(--line-2); background: var(--paper); color: var(--ink-2); cursor: pointer; }
.tabs .tab:first-child { border-radius: var(--rad) 0 0 var(--rad); }
.tabs .tab:last-child { border-radius: 0 var(--rad) var(--rad) 0; margin-left: -1px; }
.tab[aria-selected="true"] { background: var(--ink); color: #fff; border-color: var(--ink); }
.scrubrow .tab { border-radius: var(--rad); min-width: 84px; }
.readout { display: flex; flex-direction: column; gap: 12px; }
.bar-wrap { display: grid; grid-template-columns: 30px 1fr 170px; gap: 10px; align-items: center; }
.bar-wrap .wl { font-family: var(--mono); font-size: 12px; color: var(--muted); }
.track { position: relative; height: 26px; background: var(--bg-2); border: 1px solid var(--line); border-radius: 4px; overflow: hidden; }
.track .span { position: absolute; top: 0; bottom: 0; background: var(--accent); opacity: .3; }
.crisp { position: absolute; top: -1px; bottom: -1px; width: 2px; background: var(--ink); }
.nums { font-family: var(--mono); font-size: 11.5px; text-align: right; font-variant-numeric: tabular-nums; color: var(--ink-2); white-space: pre; }
.legend { font-family: var(--mono); font-size: 11px; color: var(--muted); display: flex; gap: 16px; flex-wrap: wrap; margin: 14px 0 12px; }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.swatch { width: 14px; height: 10px; display: inline-block; }
.swatch.iv { background: var(--accent); opacity: .3; } .swatch.cr { background: var(--ink); width: 3px; }
.verdict { font-family: var(--mono); font-size: 12.5px; padding: 10px 12px; border-radius: 4px; background: var(--bg-2); border: 1px solid var(--line); line-height: 1.55; color: var(--ink-2); }
.verdict .ok { color: var(--ok); font-weight: 600; }
.verdict.bad { color: var(--bad); border-color: var(--bad); }

/* example */
.usecase { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 0.8fr); gap: 36px; align-items: start; margin-bottom: 20px; }
.usecase p { margin: 0 0 14px; }
.bullets { padding-left: 20px; margin: 0; font-size: 15.5px; color: var(--ink-2); }
.bullets li { margin-bottom: 8px; }
.usecase-diagram { width: 100%; max-width: 380px; height: auto; border: 1px solid var(--line); border-radius: var(--rad); padding: 14px; justify-self: end; }

/* questions and papers */
.faq details { border-top: 1px solid var(--line); padding: 12px 0; }
.faq details:last-of-type { border-bottom: 1px solid var(--line); }
.faq summary { font-weight: 600; cursor: pointer; }
.faq p { font-size: 15.5px; color: var(--ink-2); margin: 10px 0 4px; }
.papers { padding-left: 20px; margin: 0; }
.papers li { margin-bottom: 10px; }

footer { max-width: var(--wide); margin: 0 auto; padding: 20px 24px 40px; display: flex; justify-content: space-between; border-top: 1px solid var(--line); font-size: 14px; color: var(--muted); flex-wrap: wrap; gap: 8px; }
footer a { color: var(--ink-2); }

/* responsive */
@media (max-width: 900px) {
  .stage { grid-template-columns: 1fr; }
  .stage-graph { min-height: 0; aspect-ratio: 4 / 3; }
  .stage-side { border-left: 0; border-top: 1px solid var(--line); }
  .usecase { grid-template-columns: 1fr; gap: 24px; }
  .usecase-diagram { justify-self: start; }
}
@media (max-width: 720px) {
  body { font-size: 16px; }
  .top-in { padding: 12px 16px; gap: 12px; }
  nav { gap: 12px; font-size: 14px; margin-left: 0; }
  .page { padding: 0 16px 40px; }
  .intro { padding-top: 32px; }
  h1 { font-size: 30px; }
  .lede { font-size: 17px; }
  section { margin-bottom: 56px; }
  .stage-graph { aspect-ratio: 1 / 1; }
  .features { grid-template-columns: 1fr; }
  .play { grid-template-columns: 1fr; padding: 16px; gap: 24px; }
  .bar-wrap { grid-template-columns: 28px 1fr; }
  .bar-wrap .nums { grid-column: 2; text-align: left; }
  pre { font-size: 12.5px; padding: 12px 14px; }
  footer { padding: 16px 16px 32px; }
}
@media (pointer: coarse) {
  .cellbtn { width: 44px; height: 40px; }
  .tab, .copy { padding: 9px 14px; }
  input[type=range] { height: 28px; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }