@font-face{font-family:'Google Sans Flex';font-style:normal;font-weight:1 1000;font-display:swap;src:url(fonts/google-sans-flex-latin.woff2) format('woff2')}
@font-face{font-family:'Geist Mono';font-style:normal;font-weight:400;font-display:swap;src:url(fonts/geist-mono-latin-400.woff2) format('woff2')}
@font-face{font-family:'Geist Mono';font-style:normal;font-weight:500;font-display:swap;src:url(fonts/geist-mono-latin-500.woff2) format('woff2')}

:root{
  --paper:#f5f4f0; --paper-2:#ecebe5; --paper-3:#e3e1da; --card:#fbfaf7;
  --ink:#161615; --ink-2:#47463f; --ink-3:#6f6d65; --ink-4:#b3b1a8;
  --rule:rgba(22,22,21,.13); --rule-2:rgba(22,22,21,.07);
  --red:#f42738; --blue:#2f37d8;
  --wall:#a9b6c6; --floor:#707070; --ceiling:#bba2dc; --object:#eeeeee; --new:#f39442; --window:#56c8d8; --door:#ad7756;
  --sans:'Google Sans Flex',ui-sans-serif,system-ui,-apple-system,'Segoe UI',sans-serif;
  --mono:'Geist Mono',ui-monospace,'SF Mono',Menlo,Consolas,monospace;
  --col:660px; --wide:1120px; --gutter:clamp(20px,5vw,64px);
  --r:10px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:72px}
body{margin:0;background:var(--paper);color:var(--ink-2);font:400 17.5px/1.62 var(--sans);font-optical-sizing:auto;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
img,video,canvas,svg{display:block;max-width:100%}
[hidden]{display:none!important}
::selection{background:color-mix(in srgb,var(--blue) 15%,transparent)}
a{color:inherit}
em{font-style:italic}
code{font:400 .86em var(--mono);color:var(--ink);background:var(--paper-2);padding:.08em .38em;border-radius:4px}
b,strong{color:var(--ink);font-weight:550}
h1,h2,h3,h4{color:var(--ink);margin:0;font-weight:400}
button{font:inherit;color:inherit;background:none;border:0;padding:0;cursor:pointer}
.mono{font-family:var(--mono);font-size:12px;letter-spacing:.02em}
.wrap{width:min(var(--wide),100% - 2*var(--gutter));margin-inline:auto}

/* ───────── top bar ───────── */
/* clear over the hero, whose animation runs under it; the paper backing comes in with the reading bar */
.topbar{position:fixed;inset:0 0 auto;z-index:20;height:56px;display:flex;align-items:center;gap:32px;padding:0 var(--gutter);background:transparent;transition:box-shadow .3s,background-color .3s}
.topbar.scrolled{background:color-mix(in srgb,var(--paper) 86%,transparent);backdrop-filter:saturate(1.3) blur(14px);box-shadow:0 1px 0 var(--rule)}
.brand{display:flex;align-items:center;gap:9px;font:500 19px/1 var(--sans);letter-spacing:-.02em;color:var(--ink);text-decoration:none;white-space:nowrap;opacity:0;transform:translateY(4px);transition:opacity .4s,transform .4s}
.brand img{width:24px;height:24px}
.topbar.scrolled .brand{opacity:1;transform:none}
.chapters{display:flex;gap:26px;margin-left:auto}
.chapters a{position:relative;font-size:14px;color:var(--ink-3);text-decoration:none;transition:color .2s}
.chapters a:hover,.chapters a.active{color:var(--ink)}
.chapters a::before{content:'';position:absolute;left:-11px;top:50%;width:5px;height:5px;margin-top:-2px;border-radius:50%;
  background:var(--blue);transform:scale(0);transition:transform .3s cubic-bezier(.2,.7,.2,1)}
.chapters a.active::before{transform:none}
.progress{position:absolute;left:0;right:0;bottom:-1px;height:2px;opacity:0;transition:opacity .4s}
.topbar.scrolled .progress{opacity:1}
.progress span{display:block;height:100%;width:100%;background:var(--red);clip-path:inset(0 calc((1 - var(--k,0)) * 100%) 0 0)}

/* ───────── hero ───────── */
.hero{position:relative;height:100svh;min-height:640px}
.stage{position:absolute;inset:0;overflow:hidden}
#storyCanvas{position:absolute;inset:0;width:100%;height:100%;opacity:0;transition:opacity 1.2s ease}
#storyCanvas.ready{opacity:1}
.stage::after{content:'';position:absolute;inset:0;pointer-events:none;z-index:1;background:linear-gradient(90deg,var(--paper) 0,color-mix(in srgb,var(--paper) 88%,transparent) 22%,color-mix(in srgb,var(--paper) 0%,transparent) 40%)}
.labels{position:absolute;inset:0;pointer-events:none}
.labels span{position:absolute;left:0;top:0;font:400 10.5px/1 var(--mono);letter-spacing:.03em;color:var(--ink-2);white-space:nowrap;padding-left:9px;opacity:0;transition:opacity .35s}
.labels span::before{content:'';position:absolute;left:0;top:50%;width:5px;height:1px;background:var(--ink-3)}
.panel{position:absolute;margin:0;opacity:0;pointer-events:none;will-change:opacity}
.panel-media{position:absolute;inset:0;overflow:hidden;border-radius:4px}
.panel video{position:absolute;inset:0;width:100%;height:100%;object-fit:fill}
.panel-gen{clip-path:inset(0 100% 0 0)}
.divider{position:absolute;top:0;bottom:0;left:0;width:1px;background:#fff;box-shadow:0 0 0 .5px rgba(0,0,0,.15);opacity:0}
.panel-cap{position:absolute;left:0;right:0;top:calc(100% + 12px);display:flex;justify-content:space-between;gap:16px;font:400 11px/1.3 var(--mono);letter-spacing:.03em;color:var(--ink-3);text-transform:uppercase}
.panel-cap span{background:var(--paper);padding:4px 7px;border-radius:4px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;min-width:0}
.panel-cap .cap-left{flex:0 0 auto}
.panel-cap .cap-right{text-transform:none;color:var(--ink-2)}
.panel.framed .panel-media{box-shadow:0 0 0 1px rgba(22,22,21,.22)}
.veil{position:absolute;inset:0;background:var(--paper);opacity:0;pointer-events:none}
.story-fallback{position:absolute;right:var(--gutter);top:50%;transform:translateY(-50%);width:min(52vw,760px);border-radius:var(--r)}

/* pipeline steps: keywords only, auto-advancing */
.flow{position:absolute;z-index:2;display:flex;align-items:center;gap:12px;padding:10px 12px;background:var(--paper);border:1px solid var(--rule);border-radius:12px}
.flow ol{list-style:none;margin:0;padding:0;display:flex;flex:1;gap:8px;min-width:0}
.flow li{flex:1 1 auto;min-width:0}
.flow li button{position:relative;width:100%;padding:11px 0 1px;text-align:left;font:400 13px/1.25 var(--sans);color:var(--ink-3);white-space:nowrap;overflow:hidden;text-overflow:ellipsis;transition:color .25s}
.flow li button::before,.flow li button::after{content:'';position:absolute;left:0;top:0;height:2px;border-radius:1px}
.flow li button::before{right:0;background:var(--rule)}
.flow li button::after{width:var(--p,0%);background:var(--ink)}
.flow li button:hover,.flow li.on button{color:var(--ink)}
.flow .no{font:500 10.5px var(--mono);letter-spacing:.04em;color:var(--ink-4);margin-right:7px}
.flow li.on .no{color:var(--red)}
.flow-arrow{flex:0 0 28px;height:28px;border-radius:50%;border:1px solid var(--rule);display:grid;place-items:center;color:var(--ink-3);transition:color .2s,border-color .2s}
.flow-arrow:hover{color:var(--ink);border-color:var(--ink-3)}
.flow-arrow svg{width:14px;height:14px;fill:none;stroke:currentColor;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round}

.hero-text{position:relative;z-index:2;height:100%;display:flex;flex-direction:column;justify-content:center;width:min(520px,37vw);margin-left:var(--gutter)}
/* the logo stands over the title, its left edge on the title's; it settles in once, gently */
.hero-mark{--mk:clamp(64px,6.2vw,88px);width:var(--mk);height:auto;margin:0 0 clamp(16px,1.8vw,24px);animation:mark-in 1.1s .15s cubic-bezier(.2,.7,.2,1) both}
@keyframes mark-in{from{opacity:0;transform:translateY(10px) scale(.94)}}
.hero-text h1{font:500 clamp(52px,5.4vw,82px)/.98 var(--sans);letter-spacing:-.045em;margin:0}
.hero-text h1 > .hero-subtitle{display:block;font-weight:400;font-size:.47em;line-height:1.15;letter-spacing:-.025em;color:var(--ink-2);margin-top:.3em}
.dek{font-size:16.5px;line-height:1.5;color:var(--ink-3);margin:26px 0 30px;max-width:460px}
.hero-links{display:flex;flex-wrap:wrap;gap:10px;margin:0 0 40px}
.hl{position:relative;display:inline-flex;align-items:center;gap:9px;height:40px;padding:0 17px 0 15px;border-radius:99px;font:500 14.5px/1 var(--sans);
  letter-spacing:-.005em;text-decoration:none;transition:background .25s,color .25s,border-color .25s}
.hl svg{width:16px;height:16px;fill:none;stroke:currentColor;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round}
.hl-blog,.hl-code{background:var(--ink);color:var(--paper);border:1px solid var(--ink)}
.hl-blog:hover,.hl-code:hover{background:#2c2b28}
.hl-blog i{position:relative;width:9px;height:9px;margin-left:1px;transition:transform .35s cubic-bezier(.2,.7,.2,1)}
.hl-blog i::before{content:'';position:absolute;right:0;top:0;width:6px;height:6px;border-top:1.5px solid currentColor;border-right:1.5px solid currentColor}
.hl-blog i::after{content:'';position:absolute;right:.5px;top:.5px;width:1.5px;height:11px;background:currentColor;transform-origin:50% 0;transform:rotate(45deg)}
.hl-blog:hover i{transform:translate(2px,-2px)}
.hl-code svg path{transition:transform .35s cubic-bezier(.2,.7,.2,1)}
.hl-code:hover .l{transform:translateX(-1.5px)}
.hl-code:hover .r{transform:translateX(1.5px)}
.hl-code::after{content:attr(data-tip);position:absolute;left:50%;bottom:calc(100% + 9px);padding:6px 9px 5px;border-radius:6px;background:var(--ink);color:var(--paper);
  font:500 10.5px/1 var(--mono);letter-spacing:.07em;text-transform:uppercase;white-space:nowrap;pointer-events:none;opacity:0;transform:translate(-50%,4px);
  transition:opacity .2s,transform .3s cubic-bezier(.2,.7,.2,1)}
.hl-code::before{content:'';position:absolute;left:50%;bottom:calc(100% + 5px);width:8px;height:8px;margin-left:-4px;background:var(--ink);border-radius:1.5px;
  transform:translateY(4px) rotate(45deg);opacity:0;pointer-events:none;transition:opacity .2s,transform .3s cubic-bezier(.2,.7,.2,1)}
.hl-code:hover::after,.hl-code:focus-visible::after{opacity:1;transform:translate(-50%,0)}
.hl-code:hover::before,.hl-code:focus-visible::before{opacity:1;transform:translateY(0) rotate(45deg)}
@media(prefers-reduced-motion:reduce){.hl-blog i,.hl-code svg path,.hl-code::after,.hl-code::before{transition:none}}
.affils{list-style:none;display:flex;flex-wrap:wrap;align-items:center;gap:14px 30px;padding:0;margin:0}
.affils img{height:36px;width:auto}
.affils li:first-child img{height:32px}
.affils li:last-child img{height:30px}
.placeholder{color:var(--ink-3);border-bottom:1px dashed var(--ink-4)}
/* images not loaded yet (app.js): hidden rather than the browser's placeholder, then a short fade in */
img.wait{visibility:hidden;opacity:0}
img.ready{transition:opacity .35s ease}
@media(prefers-reduced-motion:reduce){img.ready{transition:none}}

/* ───────── intro ───────── */
.intro{padding:120px 0 40px}
.intro > *{max-width:var(--col)}
.lede{font:400 clamp(20px,1.7vw,24px)/1.42 var(--sans);color:var(--ink);margin:0 0 22px;letter-spacing:-.015em}
.intro .lede{font-size:clamp(24px,2.3vw,31px);line-height:1.32;letter-spacing:-.022em}
.intro p{margin:0 0 18px}
.intro > .lede,.intro > .intro-copy{max-width:720px}
.intro-copy{font-size:17px;line-height:1.75}
.intro .intro-copy p{margin:0 0 24px}
.world-features{margin:0;padding-left:1.25em;list-style:disc}
.world-features li{padding-left:.35em;margin:0 0 18px}
.world-features li:last-child{margin-bottom:0}
.world-features li::marker{color:var(--ink-3);font-size:.75em}
.world-features strong{font-weight:550;color:var(--ink)}
/* Short editorial paragraphs follow one reading column. */
.intro p:not(.lede),.narrow,.cols p,.cols3 p{text-align:left;hyphens:manual}

/* ───────── chapters ───────── */
.chapter{padding:100px 0 32px}
.chapter-head{max-width:760px;margin-bottom:48px}
.chapter-head.small{margin-bottom:20px}
.chapter-no{font:500 11.5px var(--mono);letter-spacing:.08em;text-transform:uppercase;color:var(--ink-3);display:flex;align-items:center;gap:14px;margin:0 0 26px}
.chapter-no span{color:var(--ink)}
.chapter-no::after{content:'';flex:1;height:1px;background:var(--rule);max-width:520px}
.chapter-head h2{font:450 clamp(38px,4vw,56px)/1.04 var(--sans);letter-spacing:-.035em;margin:0 0 22px}
.sub{margin:0 0 88px}
.sub h3{font:500 21px/1.3 var(--sans);letter-spacing:-.005em;display:flex;gap:16px;align-items:baseline;margin:0 0 22px}
.sub h3 span{font:400 12px var(--mono);color:var(--ink-3);letter-spacing:.04em}
h4{font:500 22px/1.25 var(--sans);letter-spacing:-.015em;margin:72px 0 12px}
.cols{display:grid;grid-template-columns:1fr;gap:16px;max-width:var(--col);margin-bottom:34px}
.cols p{margin:0}
.narrow{max-width:var(--col);margin:0 0 30px}
.cols3{display:grid;grid-template-columns:repeat(3,1fr);gap:40px;margin:64px 0 0}
.cols3 h4{font:500 15px var(--sans);margin:0 0 10px;letter-spacing:.01em}
.cols3 p{margin:0;font-size:15.5px}

/* ───────── figures ───────── */
.fig{margin:0 0 48px}
figcaption{font-size:13.5px;line-height:1.55;color:var(--ink-3);margin-top:16px;max-width:var(--col)}
figcaption b{font:500 11.5px var(--mono);letter-spacing:.04em;color:var(--ink);margin-right:6px;text-transform:uppercase}
.fig-label{font:500 11px var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3);margin:0 0 12px;display:flex;justify-content:space-between}
.fig-note{color:var(--ink-3);margin:-24px 0 40px}
.credit{font-size:12px;max-width:none;margin-top:12px}
.ex-credit{min-height:1.55em;opacity:0;transition:opacity .5s}
@media(max-width:760px){.ex-credit{min-height:3.1em}}
.ex-credit.on{opacity:1}
.frame{position:relative;border-radius:var(--r);background:var(--paper-3)}
.frame video,.frame img{width:100%;height:auto;aspect-ratio:4/3;object-fit:cover;border-radius:var(--r)}
.ticks::after{content:'';position:absolute;inset:-8px;pointer-events:none;opacity:.7;
  background:
    linear-gradient(var(--ink-4),var(--ink-4)) left top/10px 1px no-repeat,
    linear-gradient(var(--ink-4),var(--ink-4)) left top/1px 10px no-repeat,
    linear-gradient(var(--ink-4),var(--ink-4)) right top/10px 1px no-repeat,
    linear-gradient(var(--ink-4),var(--ink-4)) right top/1px 10px no-repeat,
    linear-gradient(var(--ink-4),var(--ink-4)) left bottom/10px 1px no-repeat,
    linear-gradient(var(--ink-4),var(--ink-4)) left bottom/1px 10px no-repeat,
    linear-gradient(var(--ink-4),var(--ink-4)) right bottom/10px 1px no-repeat,
    linear-gradient(var(--ink-4),var(--ink-4)) right bottom/1px 10px no-repeat}
.tag{position:absolute;left:10px;bottom:10px;font:500 10px/1 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:#fff;background:rgba(18,18,17,.5);padding:5px 7px;border-radius:4px;pointer-events:none}

.segmented{display:flex;flex-wrap:wrap;gap:4px 22px;margin:22px 0 0;border-bottom:1px solid var(--rule)}
.player .segmented{margin:0 0 22px}
.segmented button{font-size:14px;color:var(--ink-3);padding:10px 0;margin-bottom:-1px;border-bottom:1px solid transparent;transition:color .2s,border-color .2s}
.segmented button:hover{color:var(--ink)}
.segmented button[aria-selected=true]{color:var(--ink);border-color:var(--ink)}
.segmented button[aria-pressed]{margin-left:auto;display:flex;align-items:center;gap:8px}
.segmented button[aria-pressed]::before{content:'';width:12px;height:12px;border-radius:3px;border:1px solid var(--ink-3);transition:background .2s}
.segmented button[aria-pressed=true]::before{background:var(--ink);border-color:var(--ink);box-shadow:inset 0 0 0 2px var(--paper)}

.pair{display:grid;grid-template-columns:1fr 1fr;gap:28px}
.pair.tight{gap:14px}
.trio{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.trio figure{margin:0}
.trio figcaption{font-size:12.5px;margin-top:10px}

/* 2.3 space-time: four clips, each with its time line (real cameras, frozen instants); a quiet strip on how ours were filmed */
.st{margin:0}
.st-grid{display:grid;grid-template-columns:1fr 1fr;gap:22px 28px}
.st-tag{display:flex;align-items:center;gap:6px;opacity:0;transition:opacity .3s}
.st-tag.on{opacity:1}
.st-tag::before{content:'';width:5px;height:5px;border-radius:50%;background:#fff;transition:background .3s}
.st-tag.frozen::before{background:var(--red)}
.st-time{position:relative;height:30px;margin:12px 0 0;cursor:pointer;touch-action:pan-y;outline:none}
.st-time .seg{position:absolute;top:6px;height:3px;border-radius:2px;overflow:hidden;background:color-mix(in srgb,var(--ink-4) 45%,transparent)}
.st-time .seg.frozen{background:color-mix(in srgb,var(--red) 22%,transparent)}
.st-time .seg i{position:absolute;inset:0;background:var(--ink-3);transform:scaleX(0);transform-origin:0 50%}
.st-time .seg.frozen i{background:var(--red)}
.st-time b{position:absolute;top:15px;font:500 10px/1 var(--mono);letter-spacing:.04em;color:var(--ink-4);white-space:nowrap;transform:translateX(-50%);transition:color .25s}
.st-time b.on{color:var(--ink)}
.st-time b.frozen.on{color:var(--red)}
.st-time .head{position:absolute;top:2px;width:2px;height:11px;margin-left:-1px;border-radius:1px;background:var(--ink);transition:transform .2s}
.st-time:hover .head,.st-time:focus-visible .head{transform:scaleY(1.25)}
.st-bts{display:grid;grid-template-columns:minmax(0,250px) minmax(0,1fr);gap:30px;align-items:center;margin-top:40px;padding-top:24px;border-top:1px solid var(--rule)}
.st-bts p:not(.fig-label){margin:0;font-size:14px;line-height:1.55;color:var(--ink-3)}
.st-shots{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}
.st-shots img{width:100%;aspect-ratio:16/9;object-fit:cover;border-radius:6px}

/* ───────── shared controls ───────── */
.pill{font:500 12px/1 var(--sans);color:var(--ink-2);background:color-mix(in srgb,var(--card) 90%,transparent);border:1px solid var(--rule);border-radius:99px;padding:7px 12px;backdrop-filter:blur(6px);transition:color .2s,border-color .2s,background .2s}
.pill:hover{color:var(--ink);border-color:var(--ink-4)}
.pill[aria-pressed=true]{background:var(--ink);border-color:var(--ink);color:var(--paper)}
.segmented .pill{margin:0 0 7px auto;padding:7px 12px;border:1px solid var(--rule);font-size:12px;align-self:center}
.switch{position:relative;display:flex;align-items:center;gap:9px;font-size:13.5px;color:var(--ink-3);transition:color .2s}
.switch:hover,.switch[aria-pressed=true]{color:var(--ink)}
.switch::before{content:'';width:30px;height:18px;border-radius:99px;background:var(--paper-3);box-shadow:inset 0 0 0 1px var(--rule);transition:background .25s}
.switch::after{content:'';position:absolute;left:3px;top:50%;width:12px;height:12px;margin-top:-6px;border-radius:50%;background:#fff;box-shadow:0 1px 3px rgba(0,0,0,.25);transition:transform .25s cubic-bezier(.2,.7,.2,1)}
.switch[aria-pressed=true]::before{background:var(--ink)}
.switch[aria-pressed=true]::after{transform:translateX(12px)}
.scan::after,.ex-stage[data-state=loading]::after,.floor-stage[data-state=loading]::after{content:'';position:absolute;left:0;right:0;bottom:0;height:2px;background:linear-gradient(90deg,transparent,var(--blue),transparent);background-size:40% 100%;background-repeat:no-repeat;animation:scan 1.2s linear infinite}

/* ───────── demo film ───────── */
/* No words: one wide film and a frosted play disc. Playing, the page dims around it like a cinema and the film's own colours spill
   from its edges (.film-glow: a few pixels of the current frame, blurred); a click in the dark, a pause, the end or scrolling away
   brings the lights back up. The section rises above the top bar only while dark, and drops back once the lights are up. */
.film-sec{position:relative;z-index:0;padding:40px 0 0;transition:z-index 0s .9s}
.film-sec.dark{z-index:25;transition-delay:0s}
.film-sec::before{content:'';position:fixed;inset:0;z-index:-1;background:#0e0e0d;opacity:0;pointer-events:none;transition:opacity .9s cubic-bezier(.4,0,.2,1)}
.film-sec.dark::before{opacity:.94;pointer-events:auto}
.film-frame{position:relative;width:min(100%,(100svh - 150px) * 16 / 9);margin-inline:auto}
.film-glow{position:absolute;left:-4%;top:-6%;width:108%;height:112%;filter:blur(48px) saturate(1.3);opacity:0;pointer-events:none;transition:opacity 1.4s}
.film-sec.dark .film-glow{opacity:.55}
.film{position:relative;margin:0;aspect-ratio:16/9;border-radius:14px;overflow:hidden;background:#151514;isolation:isolate;box-shadow:0 30px 60px -36px rgba(22,22,21,.45)}
.film video{width:100%;height:100%;object-fit:cover;transition:transform 1.4s cubic-bezier(.2,.7,.2,1)}
/* at rest the title card lies over the film; playing from the start, it dissolves into the film's own fade-in from black, and it
   comes back once the film has ended or been scrolled away (a pause keeps the paused frame) */
.film-cover{position:absolute;inset:0;z-index:1;width:100%;height:100%;object-fit:cover;pointer-events:none;
  transition:opacity .9s cubic-bezier(.4,0,.2,1),transform 1.4s cubic-bezier(.2,.7,.2,1)}
.film-sec.started .film-cover{opacity:0}
.film-sec:not(.started) .film:hover video,.film-sec:not(.started) .film:hover .film-cover{transform:scale(1.02)}
.film-start{position:absolute;inset:0;z-index:2;display:grid;place-items:center;background:linear-gradient(180deg,rgba(16,16,15,0) 45%,rgba(16,16,15,.22));transition:opacity .45s}
.film-start .film-disc{width:76px;height:76px;border-radius:50%;display:grid;place-items:center;background:rgba(251,250,247,.16);border:1px solid rgba(255,255,255,.42);backdrop-filter:blur(12px) saturate(1.5);box-shadow:0 12px 34px rgba(0,0,0,.18);transition:transform .5s cubic-bezier(.2,.7,.2,1),background .3s}
.film-start .film-disc{position:absolute;left:50%;top:71%;margin:-38px 0 0 -38px}   /* in the title card's empty band, between its line and its logos */
@media(max-width:600px){.film-start .film-disc{width:34px;height:34px;margin:-17px 0 0 -17px}.film-start svg{width:13px;height:13px;margin-left:2px}}   /* the whole film is the button */
.film-start:hover .film-disc{transform:scale(1.08);background:rgba(251,250,247,.26)}
.film-start svg{width:26px;height:26px;fill:#fff;margin-left:3px}
.film-sec.started:not(.paused) .film-start{opacity:0;pointer-events:none}   /* paused, the disc comes back to resume */
.film-bar{position:absolute;right:12px;bottom:22px;z-index:4;display:flex;gap:6px;opacity:0;transform:translateY(4px);transition:opacity .3s,transform .3s;pointer-events:none}
.film-sec.started .film:hover .film-bar,.film-sec.started.paused .film-bar{opacity:1;transform:none;pointer-events:auto}
@media(hover:none){.film-sec.started .film-bar{opacity:1;transform:none;pointer-events:auto}}
/* seek bar: a thin line along the film's bottom edge while it plays, thicker under the pointer; click or drag to move through it */
.film-seek{position:absolute;left:0;right:0;bottom:0;z-index:3;height:18px;cursor:pointer;touch-action:none;outline:none;opacity:0;pointer-events:none;transition:opacity .3s}
.film-sec.started .film-seek{opacity:1;pointer-events:auto}
.film-seek::before,.film-seek span{content:'';position:absolute;left:0;right:0;bottom:0;height:3px;transition:height .2s}
.film-seek::before{background:rgba(255,255,255,.3)}
.film-seek span{background:var(--red);transform:scaleX(0);transform-origin:0 50%}
.film-seek:hover::before,.film-seek:hover span,.film-seek:focus-visible::before,.film-seek:focus-visible span{height:6px}
.film-bar button{width:34px;height:34px;border-radius:50%;display:grid;place-items:center;background:rgba(16,16,15,.42);backdrop-filter:blur(6px);transition:background .2s}
.film-bar button:hover{background:rgba(16,16,15,.62)}
.film-mute::before{content:'';width:18px;height:18px;background:#fff;
  -webkit-mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 18 18'%3E%3Cpath d='M2 7h3l4-3.5v11L5 11H2z'/%3E%3Cpath d='M12 6.2a4 4 0 0 1 0 5.6M14.2 4a7 7 0 0 1 0 10' fill='none' stroke='%23000' stroke-width='1.5' stroke-linecap='round'/%3E%3C/svg%3E") center/contain no-repeat;
  mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 18 18'%3E%3Cpath d='M2 7h3l4-3.5v11L5 11H2z'/%3E%3Cpath d='M12 6.2a4 4 0 0 1 0 5.6M14.2 4a7 7 0 0 1 0 10' fill='none' stroke='%23000' stroke-width='1.5' stroke-linecap='round'/%3E%3C/svg%3E") center/contain no-repeat}
.film-sec.muted .film-mute::before{
  -webkit-mask-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 18 18'%3E%3Cpath d='M2 7h3l4-3.5v11L5 11H2z'/%3E%3Cpath d='M12 6.5l4.5 5M16.5 6.5l-4.5 5' fill='none' stroke='%23000' stroke-width='1.5' stroke-linecap='round'/%3E%3C/svg%3E");
  mask-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 18 18'%3E%3Cpath d='M2 7h3l4-3.5v11L5 11H2z'/%3E%3Cpath d='M12 6.5l4.5 5M16.5 6.5l-4.5 5' fill='none' stroke='%23000' stroke-width='1.5' stroke-linecap='round'/%3E%3C/svg%3E")}
.film-full svg{width:16px;height:16px;fill:none;stroke:#fff;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round}
.film:fullscreen{border-radius:0}
.film:fullscreen video{object-fit:contain}

/* ───────── spatial exploration ───────── */
/* inputs in blue, outputs in red: the two colours of the lab logos */
.explorer{margin:0}
/* the scene strips are built once the figure is near: their height is held from the start, so nothing below them jumps */
.ex-head{display:flex;align-items:flex-end;justify-content:space-between;gap:24px;margin:0 0 16px;min-height:131px}
/* the scene picker: a strip that scrolls sideways, with arrows and faded edges where there is more */
.ex-strip{position:relative;flex:1;min-width:0}
.ex-cases{position:relative;display:flex;gap:14px;overflow-x:auto;scroll-snap-type:x proximity;scroll-padding-inline:4px;scrollbar-width:none;padding:4px 4px 2px;
  -webkit-mask-image:linear-gradient(90deg,transparent,#000 var(--l,0px),#000 calc(100% - var(--r,0px)),transparent);mask-image:linear-gradient(90deg,transparent,#000 var(--l,0px),#000 calc(100% - var(--r,0px)),transparent)}
.ex-cases::-webkit-scrollbar{display:none}
.ex-strip.more-left .ex-cases{--l:64px}
.ex-strip.more-right .ex-cases{--r:64px}
.ex-arrow{position:absolute;top:44px;z-index:2;width:32px;height:32px;border-radius:50%;display:grid;place-items:center;background:var(--card);box-shadow:0 0 0 1px var(--rule),0 2px 8px rgba(22,22,21,.12);
  opacity:0;pointer-events:none;transition:opacity .25s}
.ex-arrow.prev{left:0}
.ex-arrow.next{right:0}
.ex-strip.more-left .prev,.ex-strip.more-right .next{opacity:1;pointer-events:auto}
.ex-arrow svg{width:14px;height:14px;fill:none;stroke:var(--ink);stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round}
.ex-case{flex:none;display:flex;flex-direction:column;align-items:center;gap:9px;scroll-snap-align:start}
.ex-scene{position:relative;display:block;overflow:hidden;border-radius:10px;outline:1.5px solid transparent;outline-offset:2px;opacity:.55;transition:outline-color .25s,opacity .25s}
.ex-scene img{display:block;width:148px;aspect-ratio:4/3;object-fit:cover}
.ex-scene:hover{opacity:.85}
.ex-case.on .ex-scene{opacity:1;outline-color:var(--ink)}
/* how far the current path has played */
.ex-bar{position:absolute;left:0;right:0;bottom:0;height:3px;background:var(--red);transform:scaleX(0);transform-origin:0 50%}
.ex-dots{display:flex;gap:5px;height:5px}
.ex-dots button{width:5px;height:5px;border-radius:3px;background:var(--ink-4);transition:background .3s,width .35s cubic-bezier(.2,.7,.2,1)}
.ex-dots button:hover{background:var(--ink-3)}
.ex-dots button[aria-current=true]{width:15px;background:var(--red)}
.ex-head .switch{margin-bottom:2px}
.ex-stage,.nav-stage,.mp-stage,.floor-stage{position:relative;overflow:hidden;border-radius:16px;background-color:var(--card);
  background-image:radial-gradient(circle,rgba(22,22,21,.075) .8px,transparent 1.1px);background-size:18px 18px;box-shadow:inset 0 0 0 1px var(--rule-2)}
.ex-stage{height:clamp(460px,44vw,560px)}
.ex-stage canvas,.nav-stage canvas,.floor-stage canvas{position:absolute;inset:0;width:100%;height:100%;cursor:grab;touch-action:pan-y!important}
/* the orbit views (and 05's #pipeCanvas): OrbitControls sets touch-action:none inline, which on a phone holds the page
   still wherever a finger lands on a 3D view; pan-y gives vertical swipes back to the page and keeps sideways drags turning the view.
   A mouse is unaffected. The playground keeps none: its objects are dragged in every direction. */
#pipeCanvas{touch-action:pan-y!important}
.ex-stage canvas:active,.nav-stage canvas:active,.floor-stage canvas:active{cursor:grabbing}
.ex-beam{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;opacity:0}
.ex-beam stop:first-child{stop-color:var(--red);stop-opacity:.1}
.ex-beam stop:last-child{stop-color:var(--red);stop-opacity:.015}
.ex-beam .edge{fill:none;stroke:var(--red);stroke-opacity:.24;stroke-width:1}
.ex-label{display:flex;align-items:center;gap:8px;margin:0;font-size:11px;letter-spacing:.08em;text-transform:uppercase;color:var(--ink)}
.ex-label i{width:7px;height:7px;border-radius:50%;background:var(--blue)}
.ex-label span{margin-left:6px;font:400 12.5px var(--sans);color:var(--ink-3);letter-spacing:0;text-transform:none}
.ex-input{position:absolute;left:24px;top:22px;display:flex;flex-direction:column;gap:12px;pointer-events:none}
.ex-thumbs{display:grid;grid-template-columns:repeat(3,58px);gap:9px;pointer-events:auto}
.explorer[data-mode=cameras] .ex-thumbs{display:none}   /* 1.1: the photos are on their cameras */
.explorer[data-mode=lift] .ex-thumbs{grid-template-columns:96px}   /* 1.2: the one photo it is given */
.ex-thumbs button{border-radius:5px;outline:1.5px solid transparent;outline-offset:1px;transition:outline-color .2s}
.ex-thumbs img{width:100%;aspect-ratio:4/3;object-fit:cover;border-radius:5px}
.ex-thumbs button.on{outline-color:var(--blue)}
/* the output is the subject: the larger share of the stage, a shadow, the beam from its camera */
.ex-card{position:absolute;right:28px;top:50%;width:min(54%,600px);transform:translateY(-50%)}
.ex-card{transition:opacity .6s,transform .8s cubic-bezier(.2,.7,.2,1)}
.ex-stage.lifting .ex-card{opacity:0;transform:translate(16px,-50%)}
.ex-card .ex-label{margin:0 0 11px}
.ex-card .ex-label i{background:var(--red)}
.ex-screen{position:relative;aspect-ratio:4/3;border-radius:12px;overflow:hidden;background:var(--paper-3);box-shadow:0 1px 2px rgba(22,22,21,.06),0 24px 48px -24px rgba(22,22,21,.32)}
.ex-out{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;opacity:0;transition:opacity .6s ease}
.ex-out.on{opacity:1}
.media-play{position:absolute;z-index:20;left:50%;top:50%;transform:translate(-50%,-50%);padding:10px 16px;border-radius:99px;background:var(--card);color:var(--ink);box-shadow:0 0 0 1px var(--rule),0 4px 18px rgba(22,22,21,.15);font:500 13px var(--sans);white-space:nowrap;pointer-events:auto}
.media-play[hidden]{display:none}
.ex-proxy{position:absolute;left:12px;bottom:12px;width:32%;aspect-ratio:4/3;border-radius:8px;overflow:hidden;box-shadow:0 0 0 2px rgba(255,255,255,.92),0 8px 20px rgba(0,0,0,.22);
  opacity:0;transform:translateY(8px) scale(.96);transform-origin:0 100%;transition:opacity .35s,transform .45s cubic-bezier(.2,.7,.2,1);pointer-events:none}
.ex-proxy.on{opacity:1;transform:none}
.ex-proxy video{width:100%;height:100%;object-fit:cover}
.ex-proxy .tag{left:7px;bottom:7px;font-size:9px;padding:4px 6px}
.ex-head .switch{margin-left:auto}
/* a hovered context photo at full size */
.ex-peek{position:absolute;z-index:4;width:300px;border-radius:10px;overflow:hidden;background:var(--paper-3);pointer-events:none;
  box-shadow:0 0 0 3px #fff,0 20px 44px -14px rgba(22,22,21,.5);opacity:0;transform:scale(.96);transform-origin:0 50%;transition:opacity .18s,transform .25s cubic-bezier(.2,.7,.2,1)}
.ex-peek.on{opacity:1;transform:none}
.ex-peek img{display:block;width:100%;aspect-ratio:4/3;object-fit:cover}
.ex-reset{position:absolute;left:20px;bottom:18px;z-index:2;display:flex;align-items:center;gap:7px;font:500 12px var(--sans);color:var(--ink-2);background:var(--card);
  border-radius:99px;padding:6px 12px 6px 10px;box-shadow:0 0 0 1px var(--rule);opacity:0;transform:translateY(4px);pointer-events:none;transition:opacity .25s,transform .25s,color .2s}
.ex-reset.on{opacity:1;transform:none;pointer-events:auto}
.ex-reset:hover{color:var(--ink)}
.ex-reset svg{width:13px;height:13px;fill:none;stroke:currentColor;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round}
/* shown when the wheel scrolls past a 3D view (zoom needs ⌘/Ctrl) */
.zoom-hint{position:absolute;left:var(--free,50%);top:50%;z-index:3;transform:translate(-50%,-50%);margin:0;padding:8px 15px;border-radius:99px;white-space:nowrap;
  background:rgba(22,22,21,.74);color:#fff;font:500 13px var(--sans);pointer-events:none;opacity:0;transition:opacity .3s}
.zoom-hint.on{opacity:1}
/* 1.3 context views: the photos and the rendering side by side at the same height (the rendering at its own 640 × 480); photos not in use fade */
.views{display:grid;grid-template-columns:1fr 1fr;gap:clamp(28px,4vw,48px);max-width:1072px;margin:0}
.views-input{display:flex;flex-direction:column}
.views .ex-label{margin:0 0 11px}
.views-output .ex-label i{background:var(--red)}
.views-photos{display:grid;grid-template-columns:repeat(3,1fr);gap:6px}
.views-photos img{width:100%;aspect-ratio:4/3;object-fit:cover;border-radius:6px;transition:opacity .4s,filter .4s}
.views-photos img.off{opacity:.22;filter:grayscale(1)}
.views-slider{padding:22px 10px 0}
.vs-track{position:relative;height:28px;cursor:pointer;touch-action:none;outline:none;--p:0}
.vs-track::before,.vs-fill{content:'';position:absolute;left:0;top:13px;height:2px;border-radius:2px}
.vs-track::before{right:0;background:var(--rule)}
.vs-fill{width:calc(var(--p) * 100%);background:var(--ink)}
.vs-track i{position:absolute;top:10px;width:8px;height:8px;margin-left:-4px;border-radius:50%;background:var(--paper);box-shadow:inset 0 0 0 1.5px var(--ink-4)}
.vs-track i:nth-of-type(2){left:50%}
.vs-track i:nth-of-type(3){left:100%}
.vs-knob{position:absolute;top:4px;left:calc(var(--p) * 100%);width:20px;height:20px;margin-left:-10px;border-radius:50%;background:#fff;
  box-shadow:0 0 0 1px var(--rule),0 2px 6px rgba(22,22,21,.22);cursor:grab;transition:transform .2s}
.vs-fill,.vs-knob{transition:left .35s cubic-bezier(.2,.7,.2,1),width .35s cubic-bezier(.2,.7,.2,1),transform .2s}
.vs-track.drag .vs-fill,.vs-track.drag .vs-knob{transition:transform .2s}
.vs-track.drag .vs-knob,.vs-track:focus-visible .vs-knob{transform:scale(1.15);cursor:grabbing}
.vs-labels{position:relative;height:20px;margin-top:4px}
.vs-labels button{position:absolute;top:0;font-size:13.5px;white-space:nowrap;color:var(--ink-3);transform:translateX(-50%);transition:color .2s}
.vs-labels button:nth-child(1){left:0}
.vs-labels button:nth-child(2){left:50%}
.vs-labels button:nth-child(3){left:100%}
.vs-labels button:hover,.vs-labels button.on{color:var(--ink)}
.views-screen{aspect-ratio:4/3}
.views-screen video{position:absolute;inset:0;opacity:0;transition:opacity .45s}
.views-screen video.on{opacity:1}

/* ───────── spatial navigation ───────── */
/* the robots as cards (as in 2.2); the map is the input and the following camera's video the output, tied by its beam.
   Each camera keeps one colour everywhere: the following camera red, the robot's head camera orange, in the map, on the video and on its window */
.navfig{margin:0;--head:var(--new)}
.nav-head{min-height:0}
.nav-stage{height:clamp(460px,44vw,560px)}
.nav-label{position:absolute;left:24px;top:22px;pointer-events:none}
.nav-card{position:absolute;right:28px;top:50%;width:min(54%,600px);transform:translateY(-50%)}
.nav-card .ex-label{margin:0 0 11px}
.nav-card .ex-label i{background:var(--red)}
.nav-screen{position:relative;aspect-ratio:4/3;border-radius:12px;overflow:hidden;background:var(--paper-3);box-shadow:0 1px 2px rgba(22,22,21,.06),0 24px 48px -24px rgba(22,22,21,.32)}
.nav-view{position:absolute;left:0;top:0;width:100%;height:100%;z-index:1;overflow:hidden;background:var(--paper-3);
  transition:left .6s cubic-bezier(.2,.7,.2,1),top .6s cubic-bezier(.2,.7,.2,1),width .6s cubic-bezier(.2,.7,.2,1),height .6s cubic-bezier(.2,.7,.2,1),border-radius .6s,box-shadow .4s}
.nav-view video,.nav-cone{position:absolute;inset:0;width:100%;height:100%}
.nav-screen[data-main=third] [data-view=first],.nav-screen[data-main=first] [data-view=third]{left:calc(69% - 12px);top:calc(69% - 12px);width:31%;height:31%;z-index:4;border-radius:8px;cursor:pointer;
  box-shadow:0 0 0 2px var(--ring),0 10px 24px -8px rgba(22,22,21,.45)}
[data-view=first]{--ring:var(--head)}
[data-view=third]{--ring:var(--red)}
.nav-view .tag{display:flex;align-items:center;gap:6px;z-index:3}
.nav-view .tag::before{content:'';width:5px;height:5px;border-radius:50%;background:var(--ring)}
.nav-screen[data-main=third] [data-view=first] .tag,.nav-screen[data-main=first] [data-view=third] .tag{left:6px;bottom:auto;top:6px;padding:3px 5px;font-size:9px}
.nav-screen[data-main=third] [data-view=first]:hover .mp-swap,.nav-screen[data-main=first] [data-view=third]:hover .mp-swap,
.nav-screen[data-main=third] [data-view=first]:focus-visible .mp-swap,.nav-screen[data-main=first] [data-view=third]:focus-visible .mp-swap{opacity:1;transform:none}
/* the head camera drawn into the following camera's video, from the same two poses */
.nav-cone{z-index:2;overflow:visible;pointer-events:none;transition:opacity .3s}
.nav-cone .side{fill:var(--head);fill-opacity:.16}
.nav-cone .edge{fill:none;stroke:var(--head);stroke-width:1.8;stroke-linejoin:round;vector-effect:non-scaling-stroke;filter:drop-shadow(0 0 1.5px rgba(22,22,21,.55))}
.nav-screen[data-main=first] .nav-cone{opacity:0}
.navfig[data-main=first] .ex-beam stop{stop-color:var(--head)}
.navfig[data-main=first] .ex-beam .edge{stroke:var(--head)}

/* ───────── robot interaction ───────── */
/* the simulation and the rendering share one screen, split at a handle; --s is the simulation's share */
@property --s{syntax:'<number>';inherits:true;initial-value:1}
.manip{margin:0}
.mp-head{display:flex;align-items:flex-start;gap:20px;margin:0 0 16px;overflow-x:auto;scrollbar-width:none;padding:4px 4px 2px;min-height:123px}
.mp-head::-webkit-scrollbar{display:none}
.mp-pick{display:flex;gap:10px}
.mp-pick + .mp-pick{padding-left:20px;border-left:1px solid var(--rule)}
.mp-chip{flex:none;display:flex;flex-direction:column;align-items:center;gap:8px;width:124px;font-size:12.5px;line-height:1.25;color:var(--ink-3);text-align:center;white-space:nowrap;transition:color .2s}
.mp-chip span{display:block;width:100%;border-radius:9px;overflow:hidden;background:#fff;box-shadow:0 0 0 1px var(--rule-2);outline:1.5px solid transparent;outline-offset:2px;opacity:.55;transition:outline-color .25s,opacity .25s}
.mp-chip img{display:block;width:100%;aspect-ratio:4/3;object-fit:cover}
.mp-chip:hover{color:var(--ink-2)}
.mp-chip:hover span{opacity:.85}
.mp-chip[aria-selected=true]{color:var(--ink)}
.mp-chip[aria-selected=true] span{opacity:1;outline-color:var(--ink)}
.mp-stage{display:grid;grid-template-columns:minmax(0,1fr) min(54%,600px);gap:clamp(28px,3.4vw,44px);align-items:center;padding:22px 28px 26px 24px}
.mp-input{display:flex;flex-direction:column;min-width:0}
.mp-input .ex-label,.mp-output .ex-label{margin:0 0 12px}
.mp-output .ex-label i{background:var(--red)}
.mp-given{display:grid;grid-template-columns:repeat(3,1fr);gap:8px}
.mp-given img{width:100%;aspect-ratio:4/3;object-fit:cover;border-radius:6px;background:#fff;box-shadow:0 0 0 1px var(--rule-2)}
.mp-sub{margin:22px 0 8px;font-size:10.5px;letter-spacing:.08em;text-transform:uppercase;color:var(--ink-3)}
.mp-plot{width:100%;height:284px;overflow:visible;cursor:col-resize;touch-action:pan-y;transition:opacity .22s}
.mp-plot.swap{opacity:0}
.mp-plot text{font:400 10px var(--mono);fill:var(--ink-3)}
.mp-plot .name{fill:var(--ink-2)}
.mp-plot .what{fill:var(--ink)}
.mp-plot .val{text-anchor:end}
.mp-plot .phase{text-anchor:middle;fill:var(--ink-4);transition:fill .3s}
.mp-plot .phase.on{fill:var(--ink)}
.mp-plot .event{text-anchor:middle}
.mp-plot .guide{stroke:var(--ink-4);stroke-dasharray:2 3}
.mp-plot .head{stroke:var(--ink);stroke-opacity:.4}
.mp-plot .joint,.mp-plot .obj,.mp-plot .other{fill:none;stroke-linejoin:round}
.mp-plot .joint{stroke:var(--new);stroke-width:1.3}
.mp-plot .obj{stroke:var(--red);stroke-width:1.6}
.mp-plot .ahead path{stroke-opacity:.26}
.mp-plot .other{stroke:var(--ink-4);stroke-opacity:.5}
.mp-plot circle{stroke:var(--card);stroke-width:1.5}
.mp-plot .jdot{fill:var(--new)}
.mp-plot .odot{fill:var(--red)}
.mp-screen{position:relative;aspect-ratio:4/3;border-radius:12px;overflow:hidden;background:var(--paper-3);cursor:ew-resize;touch-action:pan-y;
  box-shadow:0 1px 2px rgba(22,22,21,.06),0 24px 48px -24px rgba(22,22,21,.32);transition:--s .9s cubic-bezier(.2,.7,.2,1)}
.mp-screen.drag{transition:none}
.mp-deck{position:absolute;inset:0;opacity:0;transition:opacity .45s}
.mp-deck.on{opacity:1}
.mp-deck video{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.mp-gen{clip-path:inset(0 0 0 calc(var(--s) * 100%))}
.mp-track{position:absolute;inset:0;width:100%;height:100%;pointer-events:none}
.mp-track path{fill:none;stroke:var(--red);stroke-linecap:round;stroke-linejoin:round}
.mp-track .ahead{stroke-width:1.6;stroke-dasharray:3 5;stroke-opacity:.7}
.mp-track .done{stroke-width:2.2}
.mp-track .vel{stroke-width:2.2;transition:opacity .25s}
.mp-track .at{fill:var(--red);stroke:#fff;stroke-width:2}
.mp-screen .tag{z-index:3;transition:opacity .3s}
/* the two cameras: one fills the screen, the other sits in a small window, split the same way, and swaps with it on a click */
.mp-view{position:absolute;left:0;top:0;width:100%;height:100%;z-index:1;overflow:hidden;background:var(--paper-3);
  transition:left .6s cubic-bezier(.2,.7,.2,1),top .6s cubic-bezier(.2,.7,.2,1),width .6s cubic-bezier(.2,.7,.2,1),height .6s cubic-bezier(.2,.7,.2,1),border-radius .6s,box-shadow .4s}
.mp-screen[data-main=scene] [data-view=ego],.mp-screen[data-main=ego] [data-view=scene]{left:calc(69% - 12px);top:calc(69% - 12px);width:31%;height:31%;z-index:4;border-radius:8px;cursor:pointer;
  box-shadow:0 0 0 2px rgba(255,255,255,.92),0 10px 24px -8px rgba(22,22,21,.45)}
.mp-screen[data-main=scene] [data-view=ego]::after,.mp-screen[data-main=ego] [data-view=scene]::after{content:'';position:absolute;top:0;bottom:0;left:calc(var(--s) * 100%);z-index:2;width:1px;background:rgba(255,255,255,.85);pointer-events:none}
.mp-cam{position:absolute;left:6px;top:6px;z-index:3;padding:3px 5px;border-radius:3px;font-size:9px;line-height:1;letter-spacing:.05em;text-transform:uppercase;color:#fff;background:rgba(18,18,17,.5);opacity:0;transition:opacity .3s;pointer-events:none}
.mp-swap{position:absolute;right:6px;top:6px;z-index:3;display:grid;place-items:center;width:20px;height:20px;border-radius:50%;background:rgba(255,255,255,.92);box-shadow:0 1px 3px rgba(22,22,21,.25);opacity:0;transform:scale(.8);transition:opacity .25s,transform .25s;pointer-events:none}
.mp-swap svg{width:11px;height:11px;fill:none;stroke:var(--ink);stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round}
.mp-screen[data-main=scene] [data-view=ego] .mp-cam,.mp-screen[data-main=ego] [data-view=scene] .mp-cam{opacity:1}
.mp-screen[data-main=scene] [data-view=ego]:hover .mp-swap,.mp-screen[data-main=ego] [data-view=scene]:hover .mp-swap,.mp-screen[data-main=scene] [data-view=ego]:focus-visible .mp-swap,.mp-screen[data-main=ego] [data-view=scene]:focus-visible .mp-swap{opacity:1;transform:none}
.mp-screen.gen-only .tag{opacity:0}
.mp-split{position:absolute;top:0;bottom:0;left:calc(var(--s) * 100%);z-index:3;width:0;outline:none}
.mp-split::before{content:'';position:absolute;top:0;bottom:0;left:-.75px;width:1.5px;background:#fff;box-shadow:0 0 0 .5px rgba(22,22,21,.12)}
.mp-split i{position:absolute;top:50%;left:0;display:grid;place-items:center;width:30px;height:30px;margin:-15px 0 0 -15px;border-radius:50%;background:#fff;
  box-shadow:0 1px 2px rgba(22,22,21,.12),0 4px 12px rgba(22,22,21,.22);transition:transform .2s}
.mp-split svg{width:14px;height:14px;fill:none;stroke:var(--ink);stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round}
.mp-screen.drag .mp-split i,.mp-split:focus-visible i{transform:scale(1.12)}
.mp-stage .ex-peek{width:280px}

/* ───────── physics from one photo ───────── */
.phys{margin:0}
.phys .mp-head .switch{flex:none;margin:32px 4px 0 auto}
.mp-chip span{position:relative}
.ph-tag{position:absolute;left:6px;bottom:6px;font-size:9px;font-style:normal;line-height:1;letter-spacing:.03em;color:#fff;background:rgba(18,18,17,.5);padding:4px 5px;border-radius:3px}
.ph-given{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.ph-given img,.ph-tile{width:100%;aspect-ratio:4/3;border-radius:6px;background:var(--paper-3);box-shadow:0 0 0 1px var(--rule-2)}
.ph-given img{object-fit:cover}
.ph-tile{position:relative;overflow:hidden}
.ph-tile video{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;opacity:0;transition:opacity .45s}
.ph-tile video.on{opacity:1}
.ph-tile .tag{left:7px;bottom:7px;font-size:9px;padding:4px 6px}
.ph-src{margin:8px 0 0;min-height:2.9em;font-size:12px;line-height:1.45;color:var(--ink-3)}
.ph-src a{color:inherit;text-decoration-color:var(--ink-4);text-underline-offset:2px}
.phys .mp-sub{margin-top:12px}
.ph-params{display:flex;flex-wrap:wrap;gap:6px;margin:0 0 14px;padding:0;list-style:none;min-height:22px}
.ph-params li{font-size:11px;color:var(--ink-2);background:var(--paper-2);border-radius:99px;padding:3px 9px}
.mp-plot.ph-plot{height:200px}
.mp-plot .slow{fill:var(--paper-2);opacity:.8}
.mp-plot .hit{stroke:var(--new);stroke-width:1.6;stroke-linecap:round}
.mp-plot .ahead .hit{stroke-opacity:.3}
.mp-plot .earth{stroke-dasharray:3 3}
.ph-screen{position:relative;aspect-ratio:4/3;border-radius:12px;overflow:hidden;background:var(--paper-3);box-shadow:0 1px 2px rgba(22,22,21,.06),0 24px 48px -24px rgba(22,22,21,.32)}
.ph-out{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;opacity:0;transition:opacity .45s}
.ph-out.on{opacity:1}
.ph-screen canvas{position:absolute;inset:0;width:100%;height:100%;pointer-events:none}
.ph-screen canvas,.ph-hud,.ph-g{transition:opacity .3s}
.ph-screen.bare canvas,.ph-screen.bare .ph-hud,.ph-screen.bare .ph-g{opacity:0}
.ph-g{position:absolute;right:12px;top:10px;display:flex;flex-direction:row-reverse;align-items:center;gap:8px;font:500 11px var(--mono);color:#fff}
/* readable on a white gallery wall as on the Moon's black sky */
.ph-hud span,.ph-g span{padding:3px 7px;border-radius:4px;background:rgba(18,18,17,.5);text-shadow:none}
.ph-hud{gap:6px}
.ph-g svg{width:34px;height:34px;overflow:visible}
/* how slow a slowed clip was rendered, on its second, as-rendered pass */
.ph-slow{position:absolute;right:12px;top:54px;margin:0;padding:3px 7px;border-radius:4px;font-size:11px;color:#fff;background:rgba(18,18,17,.5);opacity:0;transform:translateY(-3px);transition:opacity .3s,transform .3s}
.ph-slow.on{opacity:1;transform:none}
.ph-g circle{fill:rgba(18,18,17,.3);stroke:rgba(255,255,255,.75);stroke-width:1}
.ph-g .pivot{fill:#fff;stroke:none}
.ph-g line{stroke:#fff;stroke-width:2;stroke-linecap:round;transition:opacity .3s}
.ph-g marker path{fill:#fff}
.ph-g .earth{opacity:0;stroke-dasharray:2 2.5}
.ph-g.moon .earth{opacity:.5}

/* ───────── 4.2 the floor as a map ───────── */
.floorfig{margin:0}
.floor-stage{aspect-ratio:16/7.5}
.floor-labels{position:absolute;inset:0;pointer-events:none}
.floor-labels span{position:absolute;left:0;top:0;padding:4px 7px;border-radius:4px;white-space:nowrap;font:500 10.5px/1 var(--mono);letter-spacing:.04em;
  color:var(--ink-2);background:color-mix(in srgb,var(--card) 84%,transparent);box-shadow:0 0 0 1px var(--rule-2);transition:opacity .3s}
.floor-tip{position:absolute;left:0;top:0;padding:5px 8px;border-radius:4px;white-space:nowrap;font:500 11px/1 var(--mono);letter-spacing:.02em;color:var(--ink);
  background:var(--card);box-shadow:0 0 0 1px var(--rule-2),0 2px 8px rgba(0,0,0,.08);pointer-events:none;opacity:0;transition:opacity .15s}
.floor-tip.on{opacity:1}

/* method */
.method-fig svg{width:100%;height:auto;color:var(--ink-3);font-family:var(--sans)}
.mf-node rect{fill:var(--card);stroke:var(--rule)}
.mf-node.accent rect{stroke:var(--ink-3);fill:var(--paper)}
.mf-node.out rect{stroke-dasharray:4 3;stroke:var(--ink-4)}
.mf-node .k{font:500 10px var(--mono);letter-spacing:.08em;fill:var(--ink-3)}
.mf-node .t{font:500 18px var(--sans);letter-spacing:-.01em;fill:var(--ink)}
.mf-node .s,.mf-chips .s{font-size:12px;fill:var(--ink-3)}
.mf-labels text{font:400 11px var(--mono);fill:var(--ink-3);text-anchor:middle}

/* ───────── citation, footer ───────── */
.cite{display:grid;grid-template-columns:minmax(0,180px) minmax(0,1fr);gap:40px;align-items:start;padding:72px 0 0}
.chapter .sub:last-child{margin-bottom:0}
.cite .chapter-no{margin:18px 0 0}
.cite .chapter-no::after{display:none}
.bib{position:relative;max-width:720px}
.bib pre{font:400 13px/1.7 var(--mono);color:var(--ink-2);background:var(--card);border:1px solid var(--rule);border-radius:var(--r);padding:22px 24px;margin:0;overflow:auto}
.copy{position:absolute;right:12px;top:12px;font:500 11px var(--mono);letter-spacing:.04em;color:var(--ink-3);border:1px solid var(--rule);border-radius:6px;padding:5px 10px;background:var(--paper)}
.copy:hover{color:var(--ink)}

.footer{padding:26px 0 34px;margin-top:64px;border-top:1px solid var(--rule);display:flex;justify-content:space-between;align-items:center;gap:30px}
.footer .mono{color:var(--ink-3);margin:0}
.logos{display:flex;gap:30px;align-items:center}
.logos img{height:26px;width:auto}

/* ───────── 03 play ───────── */
.code{font:400 12.5px/1.72 var(--mono);color:var(--ink-3);background:var(--card);border:1px solid var(--rule);border-radius:var(--r);padding:16px 18px;margin:0 0 18px;overflow:auto;white-space:pre}
.code .c-k{color:var(--ink)}
.code .c-s{color:#8f5a22}
.code .c-n{color:#c2581b}
.code .c-c{color:var(--ink-4)}
.code .c-line{display:inline-block;min-width:100%;margin:0 -18px;padding:0 18px;color:var(--ink-2)}
.code .c-line.live,.code .c-line:not(.ghost){background:color-mix(in srgb,var(--new) 11%,transparent);box-shadow:inset 2px 0 0 var(--new)}
.seg-note{margin-left:auto;align-self:center;color:var(--ink-4)}
.play .segmented{margin:0 0 18px}
.play-body{display:grid;grid-template-columns:minmax(0,1fr) 360px;grid-template-rows:auto auto;column-gap:30px;align-items:start}
.play-side{grid-row:1 / span 2;grid-column:2}
.play-side .code{font-size:11.5px;white-space:pre-wrap;word-break:break-word}
.play-ctx{grid-column:1;margin-top:16px}
.ctx-strip{display:grid;grid-template-columns:repeat(9,1fr);gap:4px}
.ctx-strip img{width:100%;aspect-ratio:4/3;object-fit:cover;border-radius:3px}
.play-stage{position:relative;aspect-ratio:4/3;border-radius:var(--r);overflow:hidden;background:var(--paper-3);user-select:none;--x:100%}
.play-stage canvas{position:absolute;inset:0;width:100%;height:100%;touch-action:none}
.play-video{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;pointer-events:none;opacity:0;clip-path:inset(0 0 0 var(--x));transition:opacity .35s}
.play-stage[data-state=run] .play-video{opacity:1}
.play-divider{position:absolute;top:0;bottom:0;left:var(--x);width:1px;background:rgba(255,255,255,.95);box-shadow:0 0 0 .5px rgba(0,0,0,.12);opacity:0;pointer-events:none;transition:opacity .3s}
.play-divider::after{content:'';position:absolute;top:50%;left:50%;width:28px;height:28px;margin:-14px 0 0 -14px;border-radius:50%;background:rgba(255,255,255,.95);box-shadow:0 1px 6px rgba(0,0,0,.2);cursor:ew-resize;pointer-events:auto;
  background-image:linear-gradient(var(--ink-2),var(--ink-2)),linear-gradient(var(--ink-2),var(--ink-2));background-size:1px 9px;background-repeat:no-repeat;background-position:calc(50% - 3px) 50%,calc(50% + 3px) 50%}
.play-stage[data-state=run] .play-divider{opacity:1;pointer-events:auto}
.play-stage .tag{opacity:0;transition:opacity .3s}
.play-stage .tag-b{left:auto;right:10px}
.play-stage[data-state=run] .tag{opacity:1}
.play-stage.proxy-only .tag-b::after{content:' · pending'}
.play-labels{position:absolute;inset:0;pointer-events:none}
.play-labels span{position:absolute;left:0;top:0;display:flex;flex-direction:column;gap:1px;padding:5px 8px 5px 14px;margin:-14px 0 0 0;border-radius:5px;background:rgba(18,18,17,.52);color:rgba(255,255,255,.78);font:400 10.5px/1.25 var(--mono);letter-spacing:.02em;white-space:nowrap;transition:opacity .3s;backdrop-filter:blur(3px)}
.play-labels span::before{content:'';position:absolute;left:6px;top:9px;width:4px;height:4px;border-radius:50%;background:var(--new);box-shadow:0 0 0 3px color-mix(in srgb,var(--new) 30%,transparent);animation:pulse 2.4s ease-in-out infinite}
.play-labels b{font:500 11.5px/1.2 var(--sans);color:#fff}
@keyframes pulse{50%{box-shadow:0 0 0 6px color-mix(in srgb,var(--new) 0%,transparent)}}
.play-hud{position:absolute;left:12px;top:10px;margin:0;color:#fff;text-shadow:0 1px 3px rgba(0,0,0,.4);pointer-events:none}
.play-stage[data-state=loading]::after,.play-stage[data-state=busy]::after{content:'';position:absolute;left:0;right:0;bottom:0;height:2px;background:linear-gradient(90deg,transparent,var(--new),transparent);background-size:40% 100%;background-repeat:no-repeat;animation:scan 1.2s linear infinite}
@keyframes scan{from{background-position:-40% 0}to{background-position:140% 0}}
.play-real{position:absolute;left:12px;bottom:12px;width:23%;margin:0;transition:opacity .3s;pointer-events:none}
.play-real img{width:100%;aspect-ratio:4/3;object-fit:cover;border-radius:6px;box-shadow:0 0 0 2px rgba(255,255,255,.9),0 2px 10px rgba(0,0,0,.25)}
.play-real figcaption{margin-top:6px;color:#fff;text-shadow:0 1px 3px rgba(0,0,0,.5);font-size:10px;text-transform:uppercase;letter-spacing:.06em}
.play-stage:not([data-state=explore]) .play-real{opacity:0}
/* drag to turn the view: a pill in the bottom-right corner, shown now and then (play.js) */
.play-look{position:absolute;right:12px;bottom:12px;display:flex;align-items:center;gap:8px;margin:0;padding:6px 12px 6px 10px;border-radius:99px;background:rgba(22,22,21,.6);color:#fff;font-size:10.5px;letter-spacing:.04em;pointer-events:none;opacity:0;transform:translateY(4px);transition:opacity .45s,transform .45s;-webkit-backdrop-filter:blur(6px);backdrop-filter:blur(6px)}
.play-look.on{opacity:1;transform:none}
.play-stage:not([data-state=explore]) .play-look{opacity:0}
.play-look svg{width:28px;height:13px;fill:none;stroke:currentColor;stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round;animation:look-sway 1.5s ease-in-out infinite}
@keyframes look-sway{0%,100%{transform:translateX(-3px)}50%{transform:translateX(3px)}}
@media(prefers-reduced-motion:reduce){.play-look svg{animation:none}}
/* a phone's small stage: the object labels keep only their names, the photo of this camera drops its caption, the drag hint moves up */
@media(max-width:600px){
  .play-labels span{font-size:0;gap:0;padding:4px 8px 4px 14px}
  .play-labels b{font-size:11px}
  .play-real{width:27%;left:8px;bottom:8px}
  .play-real figcaption{display:none}
  .play-look{bottom:auto;top:10px;right:10px}
}
.play-side .fig-label span{color:var(--ink-4)}
.play-outcome{font-size:13.5px;line-height:1.55;color:var(--ink-2);margin:-4px 0 26px;min-height:1.5em}
.play-outcome span{display:block;margin-top:8px;font:400 11.5px/1.6 var(--mono);color:var(--ink-3)}
.play-outcome img{display:block;width:100%;max-width:240px;margin-top:10px;border-radius:8px;border:1px solid var(--line, #e4e2dc)}
.play-try{list-style:none;padding:0;margin:0 0 26px;border-top:1px solid var(--rule)}
.play-try li{padding:10px 0;border-bottom:1px solid var(--rule);font-size:13.5px;line-height:1.45;color:var(--ink-3);cursor:default;transition:color .2s}
.play-try li:hover{color:var(--ink-2)}
.play-try b{display:block;font:500 14px var(--sans);color:var(--ink)}
.feat-body{display:grid;grid-template-columns:minmax(0,440px) minmax(0,1fr);gap:30px;align-items:start}
.feat-code{font-size:11.5px;line-height:1.8;margin:52px 0 0}
.feat-code [data-a]{display:inline-block;min-width:100%;margin:0 -18px;padding:0 18px;transition:background .25s,color .25s,box-shadow .25s}
.feat-code [data-a].on{background:color-mix(in srgb,var(--new) 13%,transparent);box-shadow:inset 2px 0 0 var(--new);color:var(--ink)}
.feat .segmented{margin:0 0 18px}
.code-note{margin:10px 0 0;font-size:12px;color:var(--ink-4)}
.feat-stage{position:relative;aspect-ratio:4/3;overflow:hidden}
.feat-stage video{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.feat-stage canvas{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;opacity:0;transition:opacity .3s}
.feat-proxy{opacity:0;transition:opacity .3s}
.feat[data-mode=proxy] .feat-proxy{opacity:1}
.feat[data-mode=physics] .feat-stage canvas{opacity:1}
.feat-hud{position:absolute;left:12px;top:10px;margin:0;display:flex;gap:12px;color:#fff;text-shadow:0 1px 3px rgba(0,0,0,.45)}
.feat-timeline{margin-top:14px}
.feat-timeline svg{width:100%;height:auto;cursor:pointer;overflow:visible}
.tl-slow{fill:color-mix(in srgb,var(--new) 12%,transparent)}
.tl-freeze{fill:color-mix(in srgb,var(--new) 26%,transparent)}
.tl-tilt{fill:none;stroke:var(--ink);stroke-width:1.6;stroke-linejoin:round}
.tl-grid{stroke:var(--rule);stroke-dasharray:2 3}
.tl-head{stroke:var(--new);stroke-width:2}
.tl-label,.tl-ev,.tl-name{font:400 11px var(--mono);fill:var(--ink-3)}
.tl-name{fill:var(--ink)}
.tl-tick{stroke:var(--ink-3)}

/* reveal */
.reveal{opacity:0;transform:translateY(14px);transition:opacity .8s ease,transform .8s cubic-bezier(.2,.7,.2,1)}
.reveal.in{opacity:1;transform:none}
/* the film section is revealed too; its delayed z-index drop keeps its place in the list, which .reveal's would otherwise replace */
.film-sec.reveal{transition:opacity .8s ease,transform .8s cubic-bezier(.2,.7,.2,1),z-index 0s .9s}
.film-sec.reveal.dark{transition-delay:0s}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal,.film-sec.reveal{opacity:1;transform:none;transition:none}
  .hero-mark{animation:none}
}

/* ───────── robotic application ───────── */
.task-ask{display:flex;align-items:baseline;gap:18px;margin:0 0 14px;padding:15px 20px;border:1px solid var(--rule);border-radius:var(--r);background:var(--card)}
.task-ask .mono{margin:0;font-size:11px;letter-spacing:.08em;text-transform:uppercase;color:var(--ink-3);white-space:nowrap}
.task-ask p:last-child{margin:0;font-size:17px;color:var(--ink)}
.affils a,.logos a{display:block;transition:opacity .2s}
.affils a:hover,.logos a:hover{opacity:.7}

/* ───────── narrow screens ───────── */
@media (max-width:900px){
  body{font-size:16px}
  .chapters{display:none}
  .topbar{height:50px}
  .hero{height:auto;min-height:0}
  .stage{position:relative;inset:auto;height:calc(132px + (100vw - 32px) * .75)}
  .hero-text{width:auto;height:auto;margin:0 var(--gutter);padding:8px 0 24px}
  .flow{padding:8px 10px;gap:8px}
  .flow li{flex:0 0 auto}
  .flow li.on{flex:1}
  .flow li:not(.on) .kw{display:none}
  .affils img{height:24px}
  .affils li:first-child img{height:22px}
  .affils li:last-child img{height:20px}
  .stage::after{background:linear-gradient(0deg,var(--paper) 0,color-mix(in srgb,var(--paper) 0%,transparent) 16%)}
  .panel-cap{display:none}
  .hero-text h1{font-size:38px}
  /* minmax(0, …): a long code line or the BibTeX scrolls inside its box instead of widening the page */
  .cols,.cols3,.pair,.trio,.play-body,.feat-body,.nav-body,.cite,.views,.mp-stage,.st-grid,.st-bts{grid-template-columns:minmax(0,1fr);gap:24px}
  .feat-code{margin-top:0}
  .play-side{grid-row:auto;grid-column:auto}
  .arrow{width:1px;height:14px;justify-self:center}
  .arrow::after{right:-3px;top:auto;bottom:-1px;border:3.5px solid transparent;border-top:5px solid var(--ink-3);border-bottom:0}
  .floor-stage{aspect-ratio:4/3}
  .footer{flex-direction:column;align-items:flex-start}
  .nav-stage{height:auto}
  .nav-stage canvas{position:relative;display:block;height:auto;aspect-ratio:4/3}
  .nav-card{position:relative;right:auto;top:auto;width:auto;transform:none;margin:0 12px 12px}
  .navfig .ex-beam{display:none}
}

:focus-visible{outline:2px solid var(--blue);outline-offset:5px}

/* Article navigation: a quiet left margin, separate from the media column. */
/* the top bar names the chapter, then the section, being read; the more specific one is underlined, the line drawing in as it changes */
.reading-title{margin-left:auto;display:flex;align-items:baseline;gap:22px;font-size:13px;color:var(--ink-3);opacity:0;transition:opacity .2s}
.reading-title .rt{position:relative;white-space:nowrap}
.reading-title .rt + .rt::before{content:'';position:absolute;left:-13px;top:2px;bottom:1px;width:1px;background:var(--ink-4);transform:rotate(20deg)}
.reading-title .now{color:var(--ink)}
.reading-title .now::after{content:'';position:absolute;left:0;right:0;bottom:-8px;height:1.5px;border-radius:1px;background:var(--red);transform-origin:0 50%;animation:rt-line .6s cubic-bezier(.2,.7,.2,1) both}
@keyframes rt-line{from{transform:scaleX(0)}}
.topbar.scrolled .reading-title{opacity:1}
.contents-mobile{display:none}
.contents{position:fixed;z-index:21;left:max(32px,calc((100vw - 1680px)/2));top:50%;width:190px;transform:translateY(-50%);opacity:0;visibility:hidden;transition:opacity .25s,visibility .25s;max-height:calc(100dvh - 144px)}
.contents[data-visible=true]{opacity:1;visibility:visible}
.contents-panel{position:absolute;top:52px;left:0;width:100%;max-height:calc(100dvh - 196px);overflow:auto;overscroll-behavior:contain;scrollbar-width:thin;scrollbar-color:var(--rule) transparent;opacity:0;visibility:hidden;transform:translateX(-7px);transition:opacity .2s,transform .3s,visibility .2s}
.contents[data-open=true] .contents-panel{opacity:1;visibility:visible;transform:none}
.contents-list,.contents-list ol{list-style:none;padding:0;margin:0}
.contents-list>li+li{margin-top:12px}
.contents-list a{position:relative;display:block;padding:3px 0;font-size:12px;line-height:1.4;text-decoration:none;color:var(--ink-3);transition:color .18s}
.contents-list>li>a{font-weight:500}
.contents-list ol{padding-top:4px}
.contents-list ol a{padding-left:16px;font-size:11.5px;font-weight:400}
.contents-list ol a::before{content:'';position:absolute;left:0;top:11px;width:6px;height:1px;background:currentColor;opacity:.4}
.contents-list a:hover,.contents-list a:focus-visible{color:var(--ink)}
.contents-list a[aria-current=location]{color:var(--blue)}
.contents-list>li[data-active=true]>a{color:var(--ink)}
.contents-list>li[data-active=true]>a[aria-current=location]{color:var(--blue)}
.contents-list a[aria-current=location]::after{content:'';position:absolute;left:-10px;top:9px;width:3px;height:8px;background:var(--blue)}
.contents-panel{padding-left:10px;margin-left:-10px;width:calc(100% + 10px)}
/* the route: a line down the margin with a stop per chapter (a box) and per section (a dot), blue as far as you have read */
.route{display:none}
@media(min-width:1280px){
  .contents-panel{display:none}
  /* the rail hangs from a fixed height, so it does not shift as a chapter's sections unfold */
  .contents{--rail-left:max(32px,calc((100vw - 1680px)/2));--media-left:max(240px,calc((100vw - var(--wide))/2));
    top:clamp(96px,calc(50dvh - 210px),250px);left:var(--rail-left);width:min(230px,calc(var(--media-left) - var(--rail-left) - 16px));transform:none}
  .route{--step:24px;position:relative;display:block;list-style:none;margin:0;padding:0}
  .route::before,.route-fill{content:'';position:absolute;left:6px;top:var(--start,0);width:1px;margin-left:-.5px}
  .route::before{height:calc(var(--end,0px) - var(--start,0px));background:var(--rule)}
  .route-fill{width:2px;margin-left:-1px;height:var(--fill,0px);border-radius:1px;background:var(--blue);transition:height .2s linear}
  .stop.is-chapter,.stop.is-part:last-child,.stop.is-part:nth-last-child(2){margin-top:14px}
  /* only the chapter being read lists its sections: they unfold under its name as you reach it */
  .stop.is-section{height:var(--step);overflow:hidden;transition:height .4s cubic-bezier(.2,.7,.2,1),opacity .3s,visibility .4s}
  .stop.is-section:not(.open){height:0;opacity:0;visibility:hidden}
  .stop a{position:relative;display:flex;align-items:center;gap:8px;height:var(--step);padding-left:24px;font-size:12px;line-height:1;text-decoration:none;color:var(--ink-3);transition:color .2s}
  /* chapters (and the overview, references, citation) read a size up and darker; sections sit under the chapter's name */
  .stop:not(.is-section) a{font-size:13px;font-weight:500;color:var(--ink-2)}
  .stop.is-section a{padding-left:46px}
  .stop.is-section.open{height:auto;min-height:var(--step)}
  .stop.is-section a{height:auto;min-height:var(--step);padding-top:4px;padding-bottom:4px;line-height:1.35}
  .stop.is-section span{white-space:normal;overflow-wrap:break-word}
  .stop a::before{content:'';position:absolute;left:3.5px;top:50%;width:5px;height:5px;margin-top:-2.5px;border-radius:50%;background:var(--paper);box-shadow:inset 0 0 0 1.2px var(--ink-4);transition:background .25s,box-shadow .25s,transform .3s cubic-bezier(.2,.7,.2,1)}
  .stop.is-chapter a::before{left:1px;width:10px;height:10px;margin-top:-5px;border-radius:2px}
  .stop.past a::before{background:var(--ink-4);box-shadow:none}
  .stop.on a::before{background:var(--blue);box-shadow:0 0 0 3px color-mix(in srgb,var(--blue) 18%,transparent);transform:scale(1.15)}
  .stop em{flex:none;width:14px;font:500 10.5px var(--mono);font-style:normal;letter-spacing:.04em;color:var(--ink-4)}
  .stop.on em,.stop.past em,.stop.open em{color:var(--ink-3)}
  .stop span{white-space:nowrap;opacity:0;transform:translateX(-4px);transition:opacity .25s,transform .3s cubic-bezier(.2,.7,.2,1)}
  .stop.is-section span{white-space:normal}
  /* named at rest: the chapter being read and the section within it */
  .contents[data-reading-text=true] .stop span{opacity:1;transform:none}
  .stop.on span,.stop.is-chapter.open span{color:var(--ink)}
  .contents:hover .stop span,.contents:focus-within .stop span{opacity:1;transform:none}
  .stop a:hover,.stop a:focus-visible{color:var(--ink)}
  main>.wrap,.footer.wrap{--reading-left:max(240px,calc((100vw - var(--wide))/2));width:min(var(--wide),calc(100% - var(--reading-left) - var(--gutter)));margin-left:var(--reading-left);margin-right:var(--gutter)}
  .sub > h3{max-width:760px}
  /* Move only editorial text into the spare right margin; media keeps its size. */
  body{--toc-text-shift:clamp(23px,calc(167px - 10vw),39px)}
  .intro > .lede,.intro-copy,.chapter-head,.sub > h3,.sub > .cols,.sub > .narrow{
    translate:var(--toc-text-shift) 0;
    transition:none;
  }

}
@media(max-width:1279px){
  .topbar{gap:18px}
  .reading-title{display:none}
  .contents-mobile{display:flex;align-items:center;gap:18px;margin-left:auto;font-size:13px;min-height:44px}
  .contents-mobile span{font-size:20px;font-weight:300;transition:transform .2s}
  .contents-mobile[aria-expanded=true] span{transform:rotate(45deg)}
  .contents{left:0;right:0;top:56px;transform:none;width:100%;max-height:none;visibility:hidden;opacity:0;padding:0 var(--gutter);background:var(--paper);border-bottom:1px solid var(--rule)}
  .contents[data-visible=true]{visibility:hidden;opacity:0}
  .contents[data-open=true]{visibility:visible;opacity:1}
  .contents-panel{position:relative;top:auto;left:auto;max-height:min(70dvh,660px);padding:20px 0 28px;margin:0;width:100%;transform:none}
  .contents-list{columns:2;column-gap:32px;max-width:800px;margin:auto}
  .contents-list>li{break-inside:avoid}
  .contents-list a{font-size:14px;padding-top:8px;padding-bottom:8px;min-height:36px}
  .contents-list ol a{font-size:13px}
  .contents-list ol a::before{top:17px}
  .contents-list a[aria-current=location]::after{left:-9px;top:14px}
}
@media(max-width:900px){.contents{top:50px}}
@media(max-width:600px){.contents-list{columns:1}.contents-panel{max-height:70dvh}.contents-list>li+li{margin-top:14px}}
@media(prefers-reduced-motion:reduce){.contents,.contents-panel,.contents-mobile span,.reading-title,.route-fill,.stop a::before,.stop span{transition:none}.reading-title .now::after{animation:none}}

/* ───────── 05 technical details ───────── */
/* the pipeline as one figure: five live cells in a row, a quiet spotlight moving along it. The four pictures are equal 4:3 cells;
   the program fills the row's height without setting it (contain:size), so no cell outgrows its column. The two videos share a
   playhead line along their lower edge. */
.pipe{position:relative;padding:28px 28px 22px;border:1px solid var(--rule);border-radius:var(--r);background:var(--card)}
.pipe-row{display:grid;grid-template-columns:1fr 24px 1fr 24px 1.5fr 24px 1fr 24px 1fr;grid-template-rows:auto auto;align-items:stretch;row-gap:12px}
.pipe-cell{position:relative;width:100%;min-width:0;overflow:hidden;aspect-ratio:4/3;border-radius:8px;background:var(--paper-3);box-shadow:0 0 0 1px var(--rule);
  transition:transform .5s cubic-bezier(.2,.7,.2,1),box-shadow .5s}
.pipe-cell.program{aspect-ratio:auto;container-type:size}   /* size containment: it fills the row without setting its height */
.pipe-cell.on{transform:translateY(-3px);box-shadow:0 0 0 1px var(--ink-3),0 22px 36px -24px rgba(22,22,21,.45)}
.pipe-cell video,.pipe-cell canvas{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;border-radius:8px}
.pipe-cell.world canvas{cursor:grab}
.pipe-cell.world canvas:active{cursor:grabbing}
.pipe-photos{position:absolute;inset:0;display:grid;grid-template-columns:repeat(3,1fr);grid-template-rows:repeat(3,1fr);gap:3px;padding:3px;background:var(--paper-2)}
.pipe-photos img{width:100%;height:100%;object-fit:cover;border-radius:3px;opacity:.78;animation:ph-turn 9s ease-in-out infinite;animation-delay:calc(var(--i) * 1s)}
@keyframes ph-turn{0%,8%{opacity:.78}3%{opacity:1}}
.pipe-code{margin:0;height:100%;box-sizing:border-box;padding:1.1em 1.4em;font:400 10px/1.7 var(--mono);font-size:min(7cqh,3.7cqw);color:var(--ink-3);background:var(--card);white-space:pre;overflow:hidden}   /* seven lines of at most 37 characters fit the cell at any width */
.pipe-code [data-a]{display:inline-block;min-width:100%;margin:0 -1.4em;padding:0 1.4em;transition:background .3s,color .3s,box-shadow .3s}
.pipe-code [data-a].on{background:color-mix(in srgb,var(--new) 13%,transparent);box-shadow:inset 2px 0 0 var(--new);color:var(--ink)}
.pipe-code .c-k{color:var(--ink)}
.pipe-code .c-s{color:#8f5a22}
.pipe-code .c-n{color:#c2581b}
.pipe-code .c-c{color:var(--ink-4)}
.pipe-time{position:absolute;left:0;right:0;bottom:0;z-index:1;height:2px;background:rgba(255,255,255,.28);pointer-events:none}
.pipe-time::after{content:'';position:absolute;inset:0;background:var(--new);transform-origin:0 50%;transform:scaleX(var(--k,0))}
.pipe-link{position:relative;align-self:center;height:1px;margin:0 5px;background:var(--rule)}
.pipe-link::after{content:'';position:absolute;left:-3px;top:-3px;width:7px;height:7px;border-radius:50%;background:var(--ink);opacity:0}
.pipe-link.on::after{animation:pipe-dot 1.5s cubic-bezier(.4,0,.2,1) both}
@keyframes pipe-dot{0%{opacity:0;transform:none}15%{opacity:1}85%{opacity:1}100%{opacity:0;transform:translateX(calc(100% + 16px))}}
/* the stage names, in the text face; the lit one darkens and gains a short rule */
.pipe-tag{position:relative;padding-top:2px;font:500 13.5px/1.3 var(--sans);letter-spacing:-.005em;color:var(--ink-4);transition:color .4s}
.pipe-tag::before{content:'';position:absolute;left:0;top:-4px;width:18px;height:1.5px;border-radius:1px;background:var(--ink);transform:scaleX(0);transform-origin:0 50%;transition:transform .5s cubic-bezier(.2,.7,.2,1)}
.pipe-row[data-on="0"] .pipe-tag:nth-of-type(1),.pipe-row[data-on="1"] .pipe-tag:nth-of-type(2),.pipe-row[data-on="2"] .pipe-tag:nth-of-type(3),.pipe-row[data-on="3"] .pipe-tag:nth-of-type(4),.pipe-row[data-on="4"] .pipe-tag:nth-of-type(5){color:var(--ink)}
.pipe-row[data-on="0"] .pipe-tag:nth-of-type(1)::before,.pipe-row[data-on="1"] .pipe-tag:nth-of-type(2)::before,.pipe-row[data-on="2"] .pipe-tag:nth-of-type(3)::before,.pipe-row[data-on="3"] .pipe-tag:nth-of-type(4)::before,.pipe-row[data-on="4"] .pipe-tag:nth-of-type(5)::before{transform:none}

@media (max-width:900px){
  .pipe{padding:18px 16px 16px}
  .pipe-row{grid-template-columns:1fr 1fr;row-gap:14px;column-gap:10px}
  .pipe-link,.pipe-tag{display:none}
  .pipe-cell.program{aspect-ratio:4/3}
}

@media(min-width:1280px) and (prefers-reduced-motion:reduce){.intro > .lede,.intro-copy,.chapter-head,.sub > h3,.sub > .cols,.sub > .narrow{transition:none}}

/* 05 in three steps under the pipeline figure, then the way to the blog: one quiet card whose pages (stills of the blog's
   figures) lie stacked and fan out under the pointer while the arrow stretches */
.steps{margin:56px 0 0}
.steps > div{padding-top:16px;border-top:1px solid var(--rule)}
.steps h4 span{margin-right:10px;font:500 11px var(--mono);letter-spacing:.06em;color:var(--ink-4)}
.steps p{color:var(--ink-2);line-height:1.6}
.blog-cta{display:grid;grid-template-columns:minmax(0,1fr) 320px;gap:40px;align-items:center;margin:64px 0 0;padding:34px 40px;
  border:1px solid var(--rule);border-radius:var(--r);background:var(--card);color:inherit;text-decoration:none;transition:border-color .3s,box-shadow .4s}
.blog-cta:hover{border-color:color-mix(in srgb,var(--ink) 24%,transparent);box-shadow:0 22px 44px -30px rgba(22,22,21,.38)}
.blog-cta h3{font:450 27px/1.16 var(--sans);letter-spacing:-.022em;margin:0 0 28px;max-width:440px}
.bc-go{display:inline-flex;align-items:center;gap:12px;font:500 14px var(--sans);color:var(--ink)}
.bc-go i{position:relative;width:22px;height:1.5px;border-radius:1px;background:currentColor;transition:width .4s cubic-bezier(.2,.7,.2,1)}
.bc-go i::after{content:'';position:absolute;right:1px;top:50%;width:7px;height:7px;box-sizing:border-box;border-top:1.5px solid currentColor;border-right:1.5px solid currentColor;transform:translateY(-50%) rotate(45deg)}   /* turned about its centre: the tip sits on the line's end */
.blog-cta:hover .bc-go i{width:36px}
.bc-pages{position:relative;height:190px}
.bc-pages img{position:absolute;left:50%;top:50%;width:236px;border-radius:7px;background:var(--card);
  box-shadow:0 0 0 1px var(--rule-2),0 14px 26px -16px rgba(22,22,21,.42);transform:translate(-50%,-50%) translate(var(--x),var(--y)) rotate(var(--r));
  transition:transform .65s cubic-bezier(.2,.7,.2,1)}
.bc-pages img:nth-child(1){--x:-12px;--y:8px;--r:-6deg}
.bc-pages img:nth-child(2){--x:12px;--y:-4px;--r:4deg}
.bc-pages img:nth-child(3){--x:0px;--y:0px;--r:-1deg}
.blog-cta:hover .bc-pages img:nth-child(1){--x:-62px;--y:14px;--r:-11deg}
.blog-cta:hover .bc-pages img:nth-child(2){--x:60px;--y:-2px;--r:9deg}
.blog-cta:hover .bc-pages img:nth-child(3){--x:0px;--y:-12px;--r:0deg}
@media(max-width:900px){
  .blog-cta{grid-template-columns:minmax(0,1fr);gap:28px;padding:26px 24px}
  .bc-pages{height:170px}
  .bc-pages img{width:210px}
}
@media(prefers-reduced-motion:reduce){.bc-pages img,.bc-go i{transition:none}}

/* contributors, before the citation: one line of names like a paper's author line, set off by quiet dots that stay at the line ends;
   a linked name keeps a faint underline that darkens under the pointer */
.people-list{list-style:none;margin:0;padding:0;max-width:760px;font-size:16px;line-height:1.95;color:var(--ink-2)}
.people-list li{display:inline;white-space:nowrap}
.people-list li:not(:last-child)::after{content:'·';margin:0 .5em 0 .55em;color:var(--ink-4)}
.people-list a{color:var(--ink);text-decoration:underline;text-decoration-color:var(--rule);text-decoration-thickness:1px;text-underline-offset:5px;transition:text-decoration-color .25s}
.people-list a:hover,.people-list a:focus-visible{text-decoration-color:currentColor}
@media(max-width:600px){.people-list{font-size:15px;line-height:1.85}}