:root{
  --paper:#EEF2F5; --panel:#F9FBFC; --ink:#18233A; --muted:#4A576E;
  --line:rgba(24,35,58,.14); --grid:rgba(24,35,58,.05);
  --k:#2C55D6; --l:#B06600; --m:#0B7A6E;
  --serif:"STIX Two Text","Noto Serif SC","Songti SC","STSong","SimSun",Georgia,serif;
  --cjk:"Noto Serif SC","Songti SC","STSong","SimSun",serif;
  color-scheme:light; box-sizing:border-box;
  padding-top:env(safe-area-inset-top,0px); padding-bottom:env(safe-area-inset-bottom,0px);
}
@media (prefers-color-scheme:dark){
  :root:not([data-theme="light"]){
    --paper:#0D1420; --panel:#131C2C; --ink:#E3E9F2; --muted:#9DAAC0;
    --line:rgba(227,233,242,.14); --grid:rgba(227,233,242,.04);
    --k:#7896FF; --l:#F0AE45; --m:#3DC6B2; color-scheme:dark;
  }
}
:root[data-theme="dark"]{
  --paper:#0D1420; --panel:#131C2C; --ink:#E3E9F2; --muted:#9DAAC0;
  --line:rgba(227,233,242,.14); --grid:rgba(227,233,242,.04);
  --k:#7896FF; --l:#F0AE45; --m:#3DC6B2; color-scheme:dark;
}
html{scroll-behavior:smooth;scroll-padding-top:calc(env(safe-area-inset-top,0px) + 72px)}
*,*::before,*::after{box-sizing:inherit}
body{margin:0;color:var(--ink);font-family:var(--serif);font-size:18px;line-height:1.7;background-color:var(--paper);
  background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);background-size:32px 32px;
  -webkit-font-smoothing:antialiased;transition:background-color .4s,color .4s}
html[data-lang="en"] .zh{display:none!important}
html:not([data-lang="en"]) .en{display:none!important}
a{color:inherit;text-decoration-color:var(--line);text-underline-offset:3px}
a:hover{text-decoration-color:currentColor}
:focus-visible{outline:2px solid var(--k);outline-offset:3px;border-radius:4px}
i,.it{font-style:italic}
sub,sup{font-size:.68em;line-height:0}
.prog{position:fixed;left:0;top:0;height:3px;width:100%;transform-origin:0 50%;transform:scaleX(0);background:var(--m);z-index:40}

/* header */
.top{position:fixed;left:0;right:0;top:0;z-index:30;padding-top:env(safe-area-inset-top,0px);border-bottom:1px solid var(--line);
  background:color-mix(in srgb,var(--paper) 82%,transparent);-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px)}
.top-in{max-width:1240px;margin:0 auto;display:flex;align-items:center;gap:12px;padding:8px 24px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;font-family:var(--cjk);font-weight:600;font-size:18px;white-space:nowrap}
.brand svg{width:26px;height:26px;flex:none}
.top nav{flex:1;min-width:0;display:flex;overflow-x:auto;scrollbar-width:none}
.top nav::-webkit-scrollbar{display:none}
.top ul{display:flex;gap:2px;list-style:none;margin:0 0 0 auto;padding:0}
.top nav a{display:block;padding:10px 11px;text-decoration:none;color:var(--muted);font-size:15px;white-space:nowrap;border-radius:8px}
.top nav a:hover{color:var(--ink);background:var(--grid)}
.lang,.theme{flex:none;min-height:44px;border:1px solid var(--line);background:var(--panel);color:var(--ink);font:inherit;font-size:15px;cursor:pointer}
.lang{min-width:56px;padding:0 14px;border-radius:999px}
.theme{width:44px;border-radius:50%;display:grid;place-items:center}
.lang:hover,.theme:hover{border-color:var(--ink)}
.theme svg{width:20px;height:20px}
.theme .moon{display:none}
:root[data-eff="dark"] .theme .sun{display:none}
:root[data-eff="dark"] .theme .moon{display:block}

/* section rail */
.rail{position:fixed;left:18px;top:50%;transform:translateY(-50%);z-index:20;display:flex;flex-direction:column;gap:14px}
.rail a{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--muted);font-size:14px;min-height:20px}
.rail a i{width:10px;height:10px;border-radius:50%;border:1.5px solid var(--muted);transition:all .3s;flex:none}
.rail a>span{opacity:0;transform:translateX(-6px);transition:all .3s;white-space:nowrap}
.rail a:hover>span,.rail a:focus-visible>span{opacity:1;transform:none}
.rail a.on{color:var(--ink)}.rail a.on i{background:var(--m);border-color:var(--m);transform:scale(1.3)}
@media (max-width:1320px){.rail{display:none}}

/* shared math */
.frac{display:inline-flex;flex-direction:column;align-items:center;vertical-align:middle;line-height:1.3}
.frac>span{padding:0 .25em;white-space:nowrap}
.frac>span:first-child{border-bottom:1.3px solid currentColor;padding-bottom:.14em}
.frac>span:last-child{padding-top:.1em}
.sfrac{display:inline-flex;flex-direction:column;align-items:center;font-size:.5em;line-height:1.05;vertical-align:1.05em;margin-left:.12em}
.sfrac>span{padding:0 .12em}
.sfrac>span:first-child{border-bottom:1px solid currentColor}
.sfrac.exp{font-size:.7em;vertical-align:1em}
.formula{display:block;width:fit-content;max-width:100%;overflow-x:auto;white-space:nowrap;font-size:21px;margin:18px 0;padding:12px 18px;background:var(--panel);border:1px solid var(--line);border-radius:12px}
.formula.disp{padding:14px 22px;line-height:1}
.disp .op{margin:0 .4em}
.formula .tag{display:inline-block;vertical-align:middle;font-size:.62em;font-style:normal;color:var(--muted);margin-right:1em;padding:.2em .6em;border:1px solid var(--line);border-radius:999px;line-height:1.3}
.disp .paren{display:inline-block;vertical-align:middle;font-size:2.4em;line-height:1;font-weight:400;transform:scaleX(.7);margin:0 -.06em;position:relative;top:-.04em}
.disp .int{display:inline-block;vertical-align:middle;font-size:1.9em;line-height:1;margin:0 .02em 0 .08em;position:relative;top:-.03em}
.disp .lim{display:inline-block;font-size:.7em;vertical-align:-1.25em;margin:0 .3em 0 -.1em}
.sqrt{display:inline-flex;align-items:flex-start}
.sqrt .rad{border-top:1.2px solid currentColor;padding:0 .1em;margin-top:.12em}
.write{clip-path:inset(0 100% 0 0);transition:clip-path 1.6s cubic-bezier(.45,.05,.25,1)}
.write.in{clip-path:inset(0 -2px 0 0)}

/* buttons */
.actions{display:flex;flex-wrap:wrap;gap:12px}
.btn{display:inline-flex;align-items:center;min-height:46px;padding:0 22px;border-radius:999px;text-decoration:none;font-size:16px;border:1px solid var(--ink)}
.btn.primary{background:var(--ink);color:var(--paper)}
.btn.primary:hover{background:var(--m);border-color:var(--m)}
.btn.ghost:hover{background:var(--panel)}

/* pinned scroll sections */
.polar{height:440vh;position:relative}
.proof{height:520vh;position:relative}
.stick{position:sticky;top:0;height:100vh;height:100svh;max-width:1240px;margin:0 auto;padding:76px 24px 20px;display:grid;gap:44px;align-items:center}
.polar .stick{grid-template-columns:minmax(0,5fr) minmax(0,6fr)}
.proof .stick{grid-template-columns:minmax(0,4fr) minmax(0,7fr)}
.steps{position:relative;align-self:center}
.step{position:absolute;left:0;right:0;top:50%;opacity:0;transform:translateY(calc(-50% + 24px));transition:opacity .5s,transform .5s;pointer-events:none}
.step.on{opacity:1;transform:translateY(-50%);pointer-events:auto}
.polar .steps{height:100%}
.proof .steps{height:340px}
.name{font-family:var(--cjk);font-weight:900;font-size:clamp(64px,9vw,128px);line-height:1;margin:0;letter-spacing:.06em}
.name span{display:inline-block;animation:rise .9s cubic-bezier(.2,.7,.2,1) both}
.name span:nth-child(2){animation-delay:.12s}.name span:nth-child(3){animation-delay:.24s}
@keyframes rise{from{opacity:0;transform:translateY(.35em) rotate(-4deg)}to{opacity:1;transform:none}}
.latin{font-style:italic;font-size:clamp(24px,2.8vw,34px);margin:12px 0 18px;color:var(--muted)}
.role{font-size:18px;max-width:30em;margin:0 0 22px}
.cue{display:flex;align-items:center;gap:12px;color:var(--muted);font-size:15px;margin:30px 0 0}
.cue>span:first-child{flex:none;display:block;width:1px;height:44px;background:linear-gradient(var(--m),transparent);animation:cue 1.8s ease-in-out infinite}
@keyframes cue{0%{transform:scaleY(0);transform-origin:top}50%{transform:scaleY(1);transform-origin:top}51%{transform-origin:bottom}100%{transform:scaleY(0);transform-origin:bottom}}
.kick{display:block;color:var(--m);font-size:15px;margin-bottom:6px}
.step h2{font-family:var(--cjk);font-weight:600;font-size:clamp(28px,3.4vw,42px);line-height:1.25;margin:0 0 14px}
.step p{margin:0 0 12px}
.polar .step p{color:var(--muted)}
.scene3d{position:relative;height:100%;min-height:0}
#scene{display:block;width:100%;height:100%;cursor:grab;touch-action:pan-y}
#scene:active{cursor:grabbing}
.read{position:absolute;right:8px;bottom:12px;background:color-mix(in srgb,var(--panel) 88%,transparent);border:1px solid var(--line);border-radius:14px;padding:10px 16px;font-variant-numeric:tabular-nums;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px)}
.read b{display:block;font-size:24px;color:var(--m);font-weight:600;line-height:1.3}
.read small{display:block;color:var(--muted);font-size:13px;line-height:1.4}
.legend{display:flex;gap:14px;font-size:13px;color:var(--muted)}
.legend i:not(.it){display:inline-block;width:10px;height:10px;border-radius:2px;margin-right:5px}
.nogl{position:absolute;inset:0;display:grid;place-items:center;color:var(--muted);margin:0}
.nogl[hidden]{display:none}
.step .n{font-variant-numeric:tabular-nums;color:var(--m);font-size:15px}
.step h3{font-family:var(--cjk);font-weight:600;font-size:clamp(24px,2.5vw,31px);line-height:1.35;margin:6px 0 12px}
.proof .step p{color:var(--muted)}
.dots{display:flex;gap:8px;position:absolute;left:0;bottom:-10px}
.dots i{width:28px;height:3px;border-radius:2px;background:var(--line);transition:background .3s}
.dots i.on{background:var(--m)}
.stage{background:var(--panel);border:1px solid var(--line);border-radius:20px;padding:16px;box-shadow:0 30px 60px -40px rgba(24,35,58,.35)}
#cv{display:block;width:100%;aspect-ratio:16/8}
#pl{display:block;width:100%;height:96px;margin-top:6px}
.chain{display:flex;flex-wrap:wrap;justify-content:center;align-items:center;gap:.3em .5em;font-size:clamp(15px,1.6vw,19px);margin:10px 0 0;line-height:1}
.chain .term{display:inline-flex;align-items:center;white-space:nowrap}
.chain .term,.chain .op{opacity:.15;transition:opacity .5s}
.chain .on{opacity:1}
.defs{text-align:center;font-size:14px;color:var(--muted);margin:8px 0 0}
.live3{display:grid;grid-template-columns:1fr auto 1fr auto 1fr;align-items:center;text-align:center;margin:8px 0 0}
.live3 b{display:block;font-size:19px;font-weight:600;font-variant-numeric:tabular-nums}
.live3 small{display:block;font-size:12px;color:var(--muted);line-height:1.3}
.live3 .ge{color:var(--muted)}
#vA{color:var(--m)}#vC{color:var(--muted)}

/* sections */
.sec{max-width:1180px;margin:0 auto;padding:96px 24px 24px}
.sec h2{font-family:var(--cjk);font-weight:600;font-size:clamp(32px,4.2vw,46px);line-height:1.2;margin:0 0 10px}
.lede{color:var(--muted);max-width:40em;margin:0 0 40px}
.topic{display:grid;grid-template-columns:260px minmax(0,1fr);gap:44px;padding:40px 0;border-top:1px solid var(--line)}
.topic figure{margin:0;transition:transform .5s cubic-bezier(.2,.7,.2,1);transform-style:preserve-3d}
.topic canvas{display:block;width:100%;aspect-ratio:1;background:var(--panel);border:1px solid var(--line);border-radius:16px}
.topic figcaption{font-size:14px;color:var(--muted);margin-top:8px;line-height:1.5}
.topic canvas.c2{margin-top:22px}
.topic canvas.c3{cursor:grab;touch-action:pan-y}
.m3{font-size:14px;color:var(--muted);margin-top:8px;font-variant-numeric:tabular-nums}
.m3v b{color:var(--m);font-weight:600;font-size:16px;margin-left:4px}
.m3bar{position:relative;height:3px;border-radius:2px;background:var(--line);margin:8px 5px 2px}
.m3bar i{position:absolute;top:-4px;left:100%;width:11px;height:11px;border-radius:50%;background:var(--m);transform:translateX(-50%)}
.m3ends{display:flex;justify-content:space-between;font-size:12px}
.arow{display:flex;align-items:center;gap:8px;font-size:16px}.arow input{flex:1;accent-color:var(--m);height:36px;min-width:0}.arow b{font-weight:600;width:2.6em;text-align:right;font-variant-numeric:tabular-nums}
.topic h3{font-family:var(--cjk);font-weight:600;font-size:clamp(23px,2.5vw,28px);line-height:1.35;margin:0 0 12px}
.topic p{margin:0 0 14px;max-width:38em}
.refs{list-style:none;padding:0;margin:0;font-size:15px;color:var(--muted)}
.refs li{margin:4px 0}

.exchange{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:48px}
.exchange h3{font-family:var(--cjk);font-weight:600;font-size:22px;margin:0 0 14px}
.exl{list-style:none;padding:0;margin:0}
.exl li{display:grid;grid-template-columns:120px minmax(0,1fr);gap:16px;padding:14px 0;border-top:1px solid var(--line)}
.exl .yr{color:var(--muted);font-variant-numeric:tabular-nums}
.exl small{display:block;color:var(--muted);font-size:15px}
.count{display:inline-block;border:1px solid var(--m);color:var(--m);border-radius:999px;font-size:13px;line-height:1.6;padding:0 9px;margin-left:8px;vertical-align:2px}

/* horizontal timeline */
.timeline{height:300vh;position:relative}
.tl-stick{position:sticky;top:0;height:100vh;height:100svh;overflow:hidden;display:flex;flex-direction:column;justify-content:center}
.tl-head{max-width:1180px;margin:0 auto 28px;padding:0 24px;width:100%}
.tl-head h2{font-family:var(--cjk);font-weight:600;font-size:clamp(32px,4.2vw,46px);line-height:1.2;margin:0 0 10px}
.tl-head .lede{margin:0}
.track{position:relative;display:flex;padding:0 max(24px,calc((100vw - 1180px)/2 + 24px));will-change:transform;width:max-content}
.track svg{position:absolute;left:0;top:0;width:100%;height:100%;overflow:visible;pointer-events:none}
.node{position:relative;width:min(330px,74vw);flex:none;padding:var(--y) 28px 0 0}
.node .yr{font-family:var(--cjk);font-weight:900;font-size:clamp(48px,6vw,80px);line-height:1;padding-left:26px;color:color-mix(in srgb,var(--ink) 14%,transparent);transition:color .4s}
.node.on .yr{color:var(--m)}
.node h4{font-family:var(--cjk);font-weight:600;font-size:20px;margin:14px 0 4px;padding-left:26px}
.node p{margin:0;color:var(--muted);font-size:16px;padding-left:26px}
.node .dot{position:absolute;left:0;top:calc(var(--y) + 2px);width:14px;height:14px;border-radius:50%;background:var(--paper);border:2px solid var(--m)}
.node.on .dot{background:var(--m)}

.grants{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
.grants li{padding:22px 24px;border:1px solid var(--line);border-radius:16px;background:var(--panel)}
.grants li:first-child{grid-column:1/-1;border-color:var(--m)}
.grants .when{font-variant-numeric:tabular-nums;color:var(--muted);font-size:15px}
.grants h3{font-family:var(--cjk);font-weight:600;font-size:20px;line-height:1.45;margin:6px 0 4px}
.grants p{margin:0;font-size:15px;color:var(--muted)}

.chips{display:flex;flex-wrap:wrap;gap:8px;margin:0 0 18px}
.chip{min-height:44px;padding:0 18px;border-radius:999px;border:1px solid var(--line);background:var(--panel);color:var(--ink);font:inherit;font-size:15px;cursor:pointer}
.chip:hover{border-color:var(--ink)}
.chip[aria-pressed="true"]{background:var(--ink);color:var(--paper);border-color:var(--ink)}
.pubs{list-style:none;margin:0;padding:0}
.pubs li{display:grid;grid-template-columns:90px minmax(0,1fr);gap:20px;padding:18px 0;border-top:1px solid var(--line)}
.pubs li[hidden]{display:none}
.py{font-variant-numeric:tabular-nums;color:var(--muted);padding-top:2px}
.pt{margin:0;font-size:19px;line-height:1.45}
.pa{margin:4px 0 0;font-size:15px;color:var(--muted)}
.pa b{color:var(--ink);font-weight:600}
.pj{margin:2px 0 0;font-size:15px}
.pj a{margin-left:6px}
.pj .pre{color:var(--l)}
.pubs li.cat-top .pj i,.pubs li.cat-adv .pj i{font-weight:600}
.note{font-size:14px;color:var(--muted);margin:16px 0 0}

.contact{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:40px;align-items:start}
.mail{display:block;font-size:clamp(22px,2.6vw,30px);text-decoration:none;margin:0 0 6px;word-break:break-all}
.mail:hover{color:var(--m)}
.addr{color:var(--muted);margin:22px 0 0}
.links{list-style:none;margin:0;padding:0}
.links a{display:flex;justify-content:space-between;gap:16px;padding:14px 0;border-top:1px solid var(--line);text-decoration:none}
.links a:hover{color:var(--m)}
.links span:last-child{color:var(--muted);font-size:15px}
footer{max-width:1180px;margin:80px auto 0;padding:28px 24px 40px;border-top:1px solid var(--line);color:var(--muted);font-size:14px;display:flex;flex-wrap:wrap;justify-content:space-between;gap:12px}

@media (max-width:900px){
  body{font-size:17px}
  .polar{height:460vh}.proof{height:560vh}
  .stick{grid-template-columns:1fr!important;grid-template-rows:auto 1fr;gap:10px;align-items:stretch;padding-top:66px}
  .polar .stick{grid-template-rows:42vh 1fr}
  .scene3d{order:-1}
  .polar .steps{height:100%}
  .step{top:0;transform:translateY(24px)}.step.on{transform:none}
  .name{font-size:clamp(52px,16vw,80px)}
  .latin{margin:6px 0 10px}
  .role{font-size:15px;line-height:1.6;margin-bottom:14px}
  .cue{display:none}
  .step h2{font-size:24px;margin-bottom:8px}
  .step p,.polar .step p{font-size:15px;line-height:1.6}
  .step .formula{font-size:17px;margin:8px 0}
  .read{right:0;bottom:0;padding:6px 12px}.read b{font-size:19px}
  .stage{order:-1;padding:10px}
  #pl{height:64px}
  .proof .steps{height:100%}
  .step h3{font-size:21px;margin:2px 0 6px}
  .dots{display:none}
  .topic{grid-template-columns:minmax(0,1fr);gap:20px}
  .topic figure{max-width:320px}
  .exchange,.contact,.grants{grid-template-columns:minmax(0,1fr)}
}
@media (max-width:600px){
  .brand .bt{display:none}
  .exl li,.pubs li{grid-template-columns:1fr;gap:4px}
  .sec{padding-top:72px}
  .live3 b{font-size:16px}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .polar,.proof,.timeline{height:auto}
  .stick{position:static;height:auto}
  .tl-stick{position:static;height:auto;overflow-x:auto;padding:80px 0 40px}
  .polar .steps,.proof .steps{height:auto}
  .step{position:static;opacity:1;transform:none;margin-bottom:28px}
  .scene3d{height:70vh}
  .name span,.cue>span:first-child{animation:none}
  .write{clip-path:none;transition:none}
  .topic figure{transition:none}
}

/* hero with a plate of key shapes */
.hero{max-width:1240px;margin:0 auto;padding:104px 24px 40px;display:grid;grid-template-columns:minmax(0,5fr) minmax(0,6fr);gap:48px;align-items:center;min-height:100vh;min-height:100svh}
.plate{min-width:0}
.tiles{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}
@media (max-width:600px){.tiles{grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}}
.tile{margin:0;border:1px solid var(--line);border-radius:14px;padding:6px 6px 8px;background:var(--panel)}
.tile canvas{display:block;width:100%;aspect-ratio:1}
.tile figcaption{font-size:13px;color:var(--muted);text-align:center;line-height:1.4}
#tSimplex,#tCube,#tEll,#tProj,#tMeis{cursor:grab;touch-action:pan-y}
@media (max-width:900px){.hero{grid-template-columns:1fr;gap:28px;padding-top:84px;min-height:0}}

/* talks, videos, service */
.tagp,.tagu{display:inline-block;border:1px solid var(--m);color:var(--m);border-radius:999px;font-size:13px;line-height:1.6;padding:0 9px;margin-left:8px;vertical-align:2px}
.tagu{border-color:var(--l);color:var(--l)}
.videos-wrap{margin-top:56px}
.videos-wrap h3{font-family:var(--cjk);font-weight:600;font-size:22px;margin:0 0 14px}
.videos{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:20px}
.videos li>a{display:block;height:100%;text-decoration:none;border:1px solid var(--line);border-radius:16px;background:var(--panel);overflow:hidden;transition:border-color .2s,transform .2s}
.videos li>a:hover{border-color:var(--m);transform:translateY(-2px)}
.vthumb{position:relative;aspect-ratio:16/9;background:linear-gradient(135deg,color-mix(in srgb,var(--k) 22%,var(--panel)),color-mix(in srgb,var(--m) 22%,var(--panel)))}
.vthumb img{display:block;width:100%;height:100%;object-fit:cover}
.vthumb::after{content:"";position:absolute;left:50%;top:50%;width:54px;height:54px;margin:-27px 0 0 -27px;border-radius:50%;background:rgba(0,0,0,.55) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M9 7l8 5-8 5z' fill='white'/%3E%3C/svg%3E") center/26px no-repeat}
.vbody{padding:14px 18px 16px}
.vbody b{display:block;font-weight:600;font-size:17px;line-height:1.4}
.vbody small{display:block;color:var(--muted);font-size:14px;margin-top:4px}
.jlist{list-style:none;margin:0;padding:0}
.jlist li{padding:10px 0;border-top:1px solid var(--line)}
.videos-wrap[hidden],#refereeBlock[hidden]{display:none}
.vbili{margin:6px 4px 0;font-size:14px}
.follow{position:relative;margin:14px 0 0;padding:12px 0 0 18px;border-left:2px solid var(--m)}
.follow .fy{display:block;font-variant-numeric:tabular-nums;color:var(--m);font-size:14px}
.follow .pt{font-size:17px}
.conf-link{text-decoration:none}
.conf-link:hover{color:var(--m)}
.conf-link .arr{color:var(--m)}