@font-face{font-family:"Source Serif 4";src:url(fonts/source-serif-4-normal-latin.woff2) format("woff2");font-weight:200 900;font-style:normal;font-display:swap;unicode-range:U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215}
@font-face{font-family:"Source Serif 4";src:url(fonts/source-serif-4-normal-latin-ext.woff2) format("woff2");font-weight:200 900;font-style:normal;font-display:swap;unicode-range:U+0100-024F,U+0259,U+1E00-1EFF,U+2020,U+20A0-20AB,U+20AD-20CF,U+2113,U+2C60-2C7F,U+A720-A7FF}
@font-face{font-family:"Source Serif 4";src:url(fonts/source-serif-4-italic-latin.woff2) format("woff2");font-weight:200 900;font-style:italic;font-display:swap;unicode-range:U+0000-00FF,U+2000-206F}
@font-face{font-family:"Source Serif 4";src:url(fonts/source-serif-4-italic-latin-ext.woff2) format("woff2");font-weight:200 900;font-style:italic;font-display:swap;unicode-range:U+0100-024F,U+1E00-1EFF}
@font-face{font-family:"IBM Plex Sans";src:url(fonts/IBMPlexSans-latin.woff2) format("woff2");font-weight:100 700;font-display:swap;unicode-range:U+0000-00FF,U+2000-206F,U+2212}
@font-face{font-family:"IBM Plex Sans";src:url(fonts/IBMPlexSans-latin-ext.woff2) format("woff2");font-weight:100 700;font-display:swap;unicode-range:U+0100-024F,U+1E00-1EFF}

:root{
  --bg:#f4f1ea;--surface:#fbf9f4;--card:rgba(251,249,244,.94);--text:#1c1812;--muted:#4a4237;--rule:#d9d1c2;--accent:#9a1d15;--accent-ink:#8e1c15;--ember:#c41c24;--focus:#0b57b0;
  --serif:"Source Serif 4",Georgia,"Times New Roman",serif;--sans:"IBM Plex Sans",system-ui,-apple-system,"Segoe UI",sans-serif;
  --top:52px;color-scheme:light
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){--bg:#0c0f13;--surface:#12161c;--card:rgba(18,22,28,.93);--text:#eef1f5;--muted:#b9c1cc;--rule:#2a313b;--accent:#ff7a45;--accent-ink:#ff9a6e;--ember:#ff5a36;--focus:#8ab8ff;color-scheme:dark}}
:root[data-theme="dark"]{--bg:#0c0f13;--surface:#12161c;--card:rgba(18,22,28,.93);--text:#eef1f5;--muted:#b9c1cc;--rule:#2a313b;--accent:#ff7a45;--accent-ink:#ff9a6e;--ember:#ff5a36;--focus:#8ab8ff;color-scheme:dark}

*{box-sizing:border-box}
[hidden]{display:none!important}
svg[hidden]{display:none}
html{-webkit-text-size-adjust:100%;scroll-padding-top:calc(var(--top) + 12px)}
body{margin:0;background:var(--bg);color:var(--text);font:400 18px/1.62 var(--serif);text-rendering:optimizeLegibility}
a{color:var(--accent-ink);text-underline-offset:2px}
:focus-visible{outline:2px solid var(--focus);outline-offset:2px}
strong{font-weight:650}
.skip-link{position:absolute;left:-999px;top:8px;background:var(--surface);color:var(--text);padding:8px 12px;z-index:50}.skip-link:focus{left:8px}

/* top bar */
.topbar{position:sticky;top:0;z-index:30;height:var(--top);display:flex;align-items:center;gap:10px;padding:0 14px;padding-left:max(14px,env(safe-area-inset-left));padding-right:max(14px,env(safe-area-inset-right));background:color-mix(in srgb,var(--bg) 88%,transparent);border-bottom:1px solid var(--rule);font:500 14px/1 var(--sans)}
.brand{display:flex;align-items:center;gap:8px;color:var(--text);text-decoration:none;font-weight:600;white-space:nowrap}
.brand-mark{width:14px;height:14px;border-radius:2px;background:linear-gradient(180deg,var(--muted) 0 50%,var(--ember) 50% 100%)}
.topnav{display:flex;gap:14px;margin-left:12px}.topnav a{color:var(--muted);text-decoration:none}.topnav a[aria-current="true"]{color:var(--text)}
.spacer{flex:1}
.chip{color:var(--muted);text-decoration:none;padding:6px 7px;border-radius:6px}.chip[aria-current="page"]{color:var(--text);background:var(--surface)}
.icon-btn{border:1px solid var(--rule);background:transparent;color:var(--text);border-radius:8px;width:34px;height:34px;display:grid;place-items:center;cursor:pointer}
:root[data-theme="dark"] .i-moon,:root:not([data-theme]) .i-moon{display:none}
:root[data-theme="light"] .i-sun{display:none}
@media (prefers-color-scheme:light){:root:not([data-theme]) .i-moon{display:inline}:root:not([data-theme]) .i-sun{display:none}}
@media (max-width:760px){.topnav{display:none}}

/* rail */
.rail{position:fixed;right:6px;top:50%;transform:translateY(-50%);z-index:20;display:flex;flex-direction:column;gap:2px;opacity:0;pointer-events:none;transition:opacity .3s}
.rail.on{opacity:1;pointer-events:auto}
.rail-dot{display:flex;align-items:center;justify-content:flex-end;gap:6px;text-decoration:none;color:var(--muted);font:500 12px/1 var(--sans);padding:3px 2px}
.rail-label{position:absolute;right:20px;white-space:nowrap;background:var(--surface);padding:3px 6px;border-radius:4px;opacity:0;pointer-events:none}
.rail-dot:hover .rail-label,.rail-dot:focus-visible .rail-label{opacity:1}
.dot{width:7px;height:7px;border-radius:50%;background:var(--rule)}.rail-dot[aria-current="true"] .dot{background:var(--ember)}
@media (max-width:1100px){.rail{display:none}}

/* story: stage + steps */
.story{position:relative;display:grid;grid-template-columns:minmax(340px,440px) 1fr}
.stage{position:sticky;top:var(--top);height:calc(100vh - var(--top));height:calc(100svh - var(--top));grid-column:2;grid-row:1;overflow:hidden;background:var(--bg)}
.stage canvas,.stagebox canvas{display:block;width:100%;height:100%;touch-action:none}
.stage canvas{touch-action:pan-y}
.steps{grid-column:1;grid-row:1;position:relative;z-index:2;padding:0 0 30vh}
.hero{min-height:calc(100svh - var(--top));display:flex;flex-direction:column;justify-content:center;padding:40px 28px 40px 32px}
.kicker{font:600 13px/1.3 var(--sans);letter-spacing:.06em;text-transform:uppercase;color:var(--accent-ink);margin:0 0 12px}
h1{font:700 clamp(34px,4.2vw,52px)/1.06 var(--serif);letter-spacing:-.01em;margin:0 0 18px}
.deck{font-size:19.5px;margin:0 0 20px}
.deck strong{color:var(--accent-ink)}
.hero-actions{display:flex;align-items:center;gap:14px;flex-wrap:wrap}
.scroll-cue{font:500 14px var(--sans);color:var(--muted)}
.deck-src{font:500 14px var(--sans);margin:18px 0 0}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;border:1px solid var(--rule);background:var(--surface);color:var(--text);font:600 15px/1 var(--sans);padding:11px 16px;border-radius:9px;cursor:pointer;text-decoration:none;min-height:44px}
.btn.primary{background:var(--accent);border-color:var(--accent);color:#fff}
:root[data-theme="dark"] .btn.primary{color:#160700}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .btn.primary{color:#160700}}
.btn.small{font-size:14px;padding:8px 12px;min-height:38px}
.step{min-height:92vh;display:flex;align-items:center;padding:6vh 20px 6vh 28px}
.card{background:var(--card);border:1px solid var(--rule);border-radius:12px;padding:20px 22px 8px;box-shadow:0 8px 30px rgba(0,0,0,.08)}
.card h2,.block h2,.ex-head h2{font:700 25px/1.2 var(--serif);margin:0 0 12px}
.card p{margin:0 0 14px}
.anchor{margin-left:8px;font:500 16px var(--sans);color:var(--muted);text-decoration:none;opacity:0}
h2:hover .anchor,.anchor:focus-visible{opacity:1}
.sparkfig{margin:6px 0 12px}
.spark{width:100%;height:150px;display:block}
.spark-cap{font:500 13px/1.4 var(--sans);color:var(--muted);margin-top:4px}
.sw{display:inline-block;width:14px;height:3px;background:var(--c);vertical-align:middle;margin:0 5px 0 0;border-radius:2px}
.stage-cap{position:absolute;left:14px;top:12px;font:600 13px var(--sans);color:var(--muted)}
.legend{position:absolute;left:12px;bottom:12px;background:var(--card);border:1px solid var(--rule);border-radius:8px;padding:7px 10px 6px;font:500 11.5px/1.25 var(--sans);color:var(--muted);width:220px}
.lg-t{display:block;color:var(--text);font-weight:600;margin-bottom:5px}
.lg-ramp{display:block;height:8px;border-radius:2px;background:linear-gradient(90deg,#8a1054 0%,#c41c24 18%,#de581e 42%,#cd872d 62%,#968e80 74%,#968e80 92%,#2474a6 100%)}
:root[data-theme="dark"] .lg-ramp{background:linear-gradient(90deg,#ff3082 0%,#ff3a30 18%,#ff7030 42%,#d69646 62%,#78828e 74%,#78828e 92%,#56b6de 100%)}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .lg-ramp{background:linear-gradient(90deg,#ff3082 0%,#ff3a30 18%,#ff7030 42%,#d69646 62%,#78828e 74%,#78828e 92%,#56b6de 100%)}}
.lg-l{display:flex;justify-content:space-between;margin-top:3px}
.lg-l span:nth-child(1){margin-left:-2px}
.lg-u{display:block;text-align:right;margin-top:1px}

@media (max-width:860px){
  .story{display:block}
  .stage{position:sticky;top:var(--top);height:42vh;height:42svh;z-index:5;border-bottom:1px solid var(--rule)}
  .steps{padding-bottom:10vh;z-index:1}
  .step,.hero{scroll-margin-top:calc(var(--top) + 42svh)}
  .hero{min-height:auto;padding:22px 18px 30px}
  h1{font-size:32px}
  .deck{font-size:18px}
  .step{min-height:auto;padding:16px 14px 46px}
  .card{box-shadow:none}
  .legend{width:150px;left:6px;bottom:6px;padding:4px 7px 3px;font-size:10.5px}
  .legend .lg-t,.legend .lg-u{display:none}
  .lg-ramp{height:6px}
  body{font-size:17.5px}
}

/* after the story */
.after{position:relative;z-index:3;background:var(--bg);border-top:1px solid var(--rule)}
.explorer{max-width:1280px;margin:0 auto;padding:46px 20px 30px}
.ex-head{max-width:720px}
.ex-head h2{font-size:30px}
.ex-grid{display:grid;grid-template-columns:minmax(300px,380px) 1fr;gap:22px;margin-top:16px;align-items:start}
.ex-view{position:sticky;top:calc(var(--top) + 10px)}
.stagebox{position:relative;height:min(74vh,720px);border:1px solid var(--rule);border-radius:12px;overflow:hidden;background:var(--bg)}
.map-ctl{position:absolute;right:10px;top:10px;display:flex;flex-direction:column;gap:6px}
.map-ctl button{width:40px;height:40px;border-radius:8px;border:1px solid var(--rule);background:var(--card);color:var(--text);font:600 20px/1 var(--sans);cursor:pointer}
.map-reset{position:absolute;right:58px;top:10px}
.map-msg{position:absolute;left:12px;bottom:64px;margin:0;font:500 13px var(--sans);color:var(--muted);background:var(--card);border-radius:6px;padding:0 6px}
.map-msg:empty{display:none}
.help{font:500 13px/1.4 var(--sans);color:var(--muted);margin:8px 0 0}
.pop{position:absolute;z-index:4;max-width:230px;background:var(--surface);border:1px solid var(--rule);border-radius:10px;padding:9px 11px;font:500 13.5px/1.4 var(--sans);box-shadow:0 8px 24px rgba(0,0,0,.18);transform:translate(10px,-100%)}
.pop p{margin:0 0 4px}
.linkish{background:none;border:0;padding:0;color:var(--accent-ink);font:inherit;cursor:pointer;text-decoration:underline;text-underline-offset:2px;text-align:left}
.pick{display:flex;gap:8px;align-items:flex-end}
.field{flex:1;display:flex;flex-direction:column;gap:5px;font:600 14px var(--sans)}
.field input{font:500 17px var(--sans);padding:10px 12px;border:1px solid var(--rule);border-radius:9px;background:var(--surface);color:var(--text);min-height:44px;width:100%}
.sugg{list-style:none;margin:4px 0 0;padding:0;border:1px solid var(--rule);border-radius:9px;background:var(--surface);font:500 15px/1.3 var(--sans);overflow:hidden}
.sugg:empty{display:none}
.sugg li{padding:9px 12px;cursor:pointer;border-bottom:1px solid var(--rule)}.sugg li:last-child{border-bottom:0}
.sugg li[aria-selected="true"],.sugg li:hover{background:var(--bg)}
.sugg span{color:var(--muted);font-size:13.5px}
.examples{font:500 14px var(--sans);color:var(--muted);display:flex;flex-wrap:wrap;gap:6px;align-items:center;margin:12px 0}
.examples button{font:600 13.5px var(--sans);border:1px solid var(--rule);background:transparent;color:var(--text);border-radius:999px;padding:6px 11px;cursor:pointer;min-height:34px}
.shared{font:600 14px var(--sans);color:var(--accent-ink)}
.result{border-top:1px solid var(--rule);padding-top:14px}
.res-empty{color:var(--muted);font-style:italic}
.result h3{font:700 23px/1.2 var(--serif);margin:0}
.res-sub{font:500 14px var(--sans);color:var(--muted);margin:2px 0 10px}
.ans{margin:0 0 10px}.ans.near{font-size:16px;color:var(--muted)}.ans.near:empty{display:none}
.hist{display:flex;align-items:flex-end;gap:2px;height:48px;margin:6px 0 14px}.hist i{flex:1;border-radius:2px 2px 0 0;min-height:2px}
@media (max-width:860px){.ex-grid{grid-template-columns:1fr}.ex-view{position:relative;top:0;order:-1}.stagebox{height:58vh;height:58svh}.explorer{padding:30px 14px}}

.prose{max-width:760px;margin:0 auto;padding:10px 20px 40px}
.block{margin:40px 0}.block.wide{max-width:none}
.block p{margin:0 0 14px}
.fig{margin:0}.fig-h{font:600 15px var(--sans);margin:0 0 8px}
.tablewrap{overflow-x:auto;border:1px solid var(--rule);border-radius:10px}
table.pub{border-collapse:collapse;width:100%;font:500 14px/1.35 var(--sans)}
table.pub th,table.pub td{padding:8px 10px;border-bottom:1px solid var(--rule);text-align:left;vertical-align:top}
table.pub th{font-weight:600;background:var(--surface);position:sticky;top:0}
table.pub .n{text-align:right;font-variant-numeric:tabular-nums;white-space:nowrap}
table.pub .sub{color:var(--muted);font-size:12.5px}
table.pub .chk{color:var(--muted);font-size:12.5px;min-width:150px}
.more{margin-top:10px}
.fig-note{font:500 13px/1.45 var(--sans);color:var(--muted);margin:8px 0 0}
.sources{font-size:15.5px;padding-left:20px}.sources li{margin:0 0 8px}
.share{margin:22px 0}.share-row{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.share-label{font:600 14px var(--sans);margin-right:4px}
.ic{display:inline-grid;place-items:center;width:40px;height:40px;border-radius:50%;border:1px solid var(--rule);background:var(--surface);color:var(--text);cursor:pointer}
.share-msg{font:500 13px var(--sans);color:var(--muted);margin:6px 0 0;min-height:1em}
.site-footer{display:flex;gap:18px;justify-content:center;flex-wrap:wrap;padding:26px 16px 40px;font:500 14px var(--sans);color:var(--muted);border-top:1px solid var(--rule)}
.site-footer a{color:var(--muted)}
.place-page main{max-width:640px;margin:10vh auto;padding:0 20px}
@media (prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}
.res-actions{display:flex;gap:8px;flex-wrap:wrap;margin-top:4px}