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.motivation-visual {
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  display: grid; grid-template-columns: .84fr 1.16fr; gap: 18px; align-items: stretch;
  scroll-margin-top: 78px;
}
.motivation-visual__story {
  display: grid; gap: 10px;
}
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}
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}
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}
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}
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}
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  background: var(--orange-wash) !important;
}
.motivation-visual__negative span { color: var(--orange-ink); }
.motivation-figure {
  margin: 0; padding: 16px;
  border: 1px solid var(--line); border-radius: 10px; background: var(--surface);
  display: flex; flex-direction: column; justify-content: center;
}
.motivation-figure__link {
  display: block; border-radius: 6px; overflow: hidden;
}
.motivation-figure__link:hover { text-decoration: none; }
.motivation-figure img {
  display: block; width: 100%; height: auto; border-radius: 6px; background: white;
}
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  margin-top: 11px; font: 13px/1.55 var(--sans); color: var(--muted);
}
.motivation-figure figcaption b { color: var(--soft); }
.equation-card{margin:28px auto!important;padding:21px 24px;border-left:3px solid var(--blue);background:var(--blue-wash);overflow:auto}.equation-card>span{font:700 11px var(--sans);letter-spacing:.1em;text-transform:uppercase;color:var(--blue-ink)}.equation-card mjx-container[display=true]{margin:.8em 0 .2em!important}.equation-card--plain{border-left-color:var(--muted);background:var(--line2)}
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.balance-map{display:grid;grid-template-columns:1fr 98px 1fr;gap:15px;align-items:center;margin-top:30px!important}.balance-map>div{padding:25px;border:1px solid var(--line);border-radius:10px;background:var(--surface);text-align:center}.balance-map__learn{background:var(--blue-wash)!important;border-color:color-mix(in srgb,var(--blue) 30%,var(--line))!important}.balance-map span{display:block;margin-bottom:9px;font:700 11px var(--sans);letter-spacing:.1em;text-transform:uppercase;color:var(--muted)}.balance-map b{display:block;font-size:16px}.balance-map i{font-style:normal;color:var(--muted)}.balance-map svg{width:100%;fill:none;stroke:var(--blue);stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}.margin-note{margin:18px auto 0;max-width:var(--col);padding-left:18px;border-left:2px solid var(--orange);font-size:16px;color:var(--soft)}
.theorems{display:grid;gap:11px;margin-top:26px!important}.theorems details{border:1px solid var(--line);border-radius:8px;background:var(--surface);overflow:hidden}.theorems summary{display:grid;grid-template-columns:82px 1fr auto;gap:14px;align-items:center;padding:18px 20px;list-style:none;cursor:pointer}.theorems summary::-webkit-details-marker{display:none}.theorems summary:hover{background:var(--line2)}.theorems summary span{font:700 11px var(--sans);letter-spacing:.08em;text-transform:uppercase;color:var(--blue-ink)}.theorems summary b{font-size:17px}.theorems summary i{font:20px var(--sans);font-style:normal;color:var(--muted)}.theorems details>div{padding:3px 22px 20px;border-top:1px solid var(--line2)}.theorems details>div p{font-size:16px;color:var(--soft)}.theorems mjx-container[display=true]{overflow-x:auto;overflow-y:hidden}
.result-chart{margin-top:30px!important;padding:24px;border:1px solid var(--line);border-radius:10px;background:var(--surface)}.result-chart__head{display:flex;justify-content:space-between;margin-bottom:22px}.result-chart__head b{font-size:17px}.result-chart__head span{font:12px var(--sans);color:var(--muted)}.result-row{display:grid;grid-template-columns:65px 1fr 52px;gap:12px;align-items:center;margin:14px 0}.result-row>span{font:13px var(--sans);color:var(--muted)}.result-row>div{height:18px;background:var(--line2);border-radius:3px;overflow:hidden}.result-row i{display:block;width:var(--w);height:100%;background:var(--muted)}.result-row output{font:600 12px var(--mono);text-align:right}.result-row--ours span,.result-row--ours output{font-weight:700;color:var(--blue-ink)}.result-row--ours i{background:var(--blue)}
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.benchmark-details{margin-top:26px!important}.benchmark-details>summary{cursor:pointer;font:600 13px var(--sans);color:var(--blue-ink)}.benchmark-details>summary span{margin-left:5px}.table-wrap{overflow-x:auto;margin-top:14px}table{width:100%;min-width:800px;border-collapse:collapse;font:12.5px/1.4 var(--sans);background:var(--surface)}th,td{padding:10px 12px;border-bottom:1px solid var(--line2);text-align:center}th{font-size:11px;text-transform:uppercase;letter-spacing:.05em;color:var(--muted)}th:first-child,td:first-child,th:nth-child(2),td:nth-child(2){text-align:left}.ours{background:var(--blue-wash);color:var(--blue-ink);font-weight:600}
.closing{margin-top:64px!important;padding:30px 32px;border-top:2px solid var(--ink);border-bottom:1px solid var(--line)}.closing p{margin:0 0 8px;font:700 11px var(--sans);letter-spacing:.1em;text-transform:uppercase;color:var(--orange-ink)}.closing h2{max-width:820px;margin:0;font-size:clamp(25px,3.4vw,34px)}
footer{max-width:var(--col);margin:80px auto 0;padding-top:34px;border-top:1px solid var(--line)}footer h3{font-size:19px}.bibtex{position:relative;margin-top:15px;border:1px solid var(--line);border-radius:7px;background:var(--line2)}.bibtex pre{margin:0;padding:18px 70px 18px 18px;overflow:auto;font:12px/1.55 var(--mono);color:var(--soft)}.bibtex button{position:absolute;right:10px;top:10px;padding:5px 10px;border:1px solid var(--line);border-radius:5px;background:var(--surface);font:12px var(--sans);color:var(--muted);cursor:pointer}
.reveal{opacity:0;transform:translateY(12px);transition:opacity .55s,transform .55s}.reveal.in{opacity:1;transform:none}mjx-container{max-width:100%}
@media(max-width:1000px){.page{grid-template-columns:1fr}.toc{display:none}.article{padding-top:38px}}
@media(max-width:760px){body{font-size:17px}.topbar__inner{padding-inline:18px}.topnav>a:not(.topnav__pill){display:none}.page{display:block;padding:0 20px;overflow:hidden}.article{width:100%;min-width:0}.article>section>*,.article>footer>*{max-width:100%;min-width:0}.hero h1{font-size:53px}.hero__tagline{font-size:21px}.hero__lead{font-size:17.5px}.story-map{grid-template-columns:1fr}.story-arrow{width:60px;justify-self:center;transform:rotate(90deg)}.takeaways{padding-top:20px}.term-grid,.result-triptych{grid-template-columns:1fr}.gate-rule{grid-template-columns:1fr}.gate-rule__verb{padding:13px}.mass-lab__controls{grid-template-columns:1fr}.mass-row{grid-template-columns:120px 1fr 48px;gap:8px}.balance-map{grid-template-columns:1fr}.balance-map svg{width:65px;justify-self:center;transform:rotate(90deg)}.theorems summary{grid-template-columns:70px 1fr auto;gap:8px;padding:16px 14px}.theorems summary b{font-size:15.5px}.theorems details>div{padding:3px 16px 17px}.theorems details>div p{font-size:16px}.equation-card{padding:18px 15px}.equation-card mjx-container{font-size:86%!important}.result-chart{padding:19px 15px}.result-triptych article{padding:22px}.closing{padding:26px 0}.section{padding-top:70px}}
@media(max-width:760px){.motivation-visual{grid-template-columns:1fr}.motivation-figure{padding:12px}.motivation-visual__story article{padding:15px 16px}}
@media(max-width:470px){.mass-row{grid-template-columns:1fr 44px}.mass-row>div{grid-column:1/-1}.hero h1{font-size:48px}.story-map__input,.story-map__output{min-height:155px}.result-chart__head{display:block}.result-chart__head span{display:block;margin-top:3px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.reveal{opacity:1;transform:none;transition:none}.mass-row>span i{transition:none}}
/* Strong mobile containment for browsers with a wider layout viewport. */
@media(max-width:900px){
 html,body{width:100%;max-width:100%;overflow-x:hidden}
 .topbar__inner{width:100%;max-width:100%;padding-inline:18px}
 .topnav>a:not(.topnav__pill){display:none}
 .page{display:block;width:100%;max-width:100%;padding-inline:20px;overflow:hidden}
 .article,.article>section,.article>footer{width:100%;max-width:100%;min-width:0}
 .article>section>*,.article>footer>*{width:auto;max-width:100%;min-width:0}
 .hero .eyebrow,.hero__tagline,.hero__lead,.byline{overflow-wrap:anywhere}
 .story-map,.takeaways,.term-grid,.gate-rule,.mass-lab,.motivation-visual,.balance-map,.theorems,.result-chart,.result-triptych,.benchmark-details,.closing{width:100%!important;max-width:100%!important;min-width:0}
 .equation-card,.theorems details>div,.table-wrap{max-width:100%;overflow-x:auto;overflow-y:hidden}
}

/* ====================== One shared content column ======================
   Text, diagrams, interactions, theorems, and charts use the same edges. */
:root {
  --content: 820px;
  --col: var(--content);
  --wide: var(--content);
}

.article > section > *,
.article > footer > *,
.article > section > .story-map,
.article > section > .takeaways,
.article > section > .term-grid,
.article > section > .gate-rule,
.article > section > .mass-lab,
.article > section > .motivation-visual,
.article > section > .balance-map,
.article > section > .theorems,
.article > section > .result-chart,
.article > section > .result-triptych,
.article > section > .benchmark-details,
.article > section > .closing,
.margin-note,
footer {
  width: 100%;
  max-width: var(--content);
  margin-left: auto;
  margin-right: auto;
}

/* Keep narrow semantic elements aligned rather than independently centered. */
.hero__tagline,
.hero__lead,
.byline,
.figure-note,
.section > p,
.section > h2,
.section__label,
.subhead,
.equation-card {
  width: 100%;
  max-width: var(--content);
}

@media (max-width: 900px) {
  :root { --content: 100%; }
}
/* Full paper title in the hero. */
.hero h1 {
  font-size: clamp(40px, 5.4vw, 60px);
  line-height: 1.04;
  letter-spacing: -.032em;
}
@media (max-width: 760px) {
  .hero h1 { font-size: clamp(34px, 10vw, 47px); }
}

/* FlowBalance story: one training round and its distributional consequence. */
.flow-round {
  width: 100%; max-width: var(--content); margin: 28px auto;
  display: grid; grid-template-columns: 1fr 54px 1fr 54px 1fr;
  gap: 10px; align-items: center;
}
.flow-round article {
  min-height: 172px; padding: 21px 19px;
  border: 1px solid var(--line); border-radius: 9px; background: var(--surface);
}
.flow-round article > span {
  width: 24px; height: 24px; display: grid; place-items: center;
  border-radius: 50%; border: 1px solid color-mix(in srgb,var(--blue) 42%,var(--line));
  font: 700 11px var(--sans); color: var(--blue-ink);
}
.flow-round article b { display: block; margin: 16px 0 6px; font-size: 17px; }
.flow-round article p { margin: 0; font: 13px/1.55 var(--sans); color: var(--muted); }
.flow-round svg { width: 100%; fill: none; stroke: var(--muted); stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
.bridge-copy { margin-top: 28px !important; }
.story-callout {
  width: 100%; max-width: var(--content); margin: 22px auto 0;
  padding: 17px 20px; border-left: 2px solid var(--orange); background: var(--orange-wash);
  font-size: 16px; line-height: 1.62; color: var(--soft);
}
.flow-consequence {
  width: 100%; max-width: var(--content); margin: 24px auto 0;
  padding: 21px 24px; border: 1px solid var(--line); border-radius: 8px; background: var(--surface);
  text-align: center; overflow-x: auto;
}
.flow-consequence > span {
  font: 700 11px var(--sans); letter-spacing: .1em; text-transform: uppercase; color: var(--blue-ink);
}
.flow-consequence p { margin: 6px 0 0; font-size: 15px; color: var(--soft); }
@media(max-width:760px){
  .flow-round { grid-template-columns: 1fr; }
  .flow-round article { min-height: 0; }
  .flow-round svg { width: 54px; justify-self: center; transform: rotate(90deg); }
  .flow-consequence { padding: 18px 14px; text-align: left; }
  .flow-consequence mjx-container { font-size: 86% !important; }
}

/* Inline theory belongs to the surrounding method narrative. */
.inline-theory {
  width: 100%; max-width: var(--content); margin: 24px auto 0;
  border-top: 1px solid var(--line); border-bottom: 1px solid var(--line);
  background: transparent;
}
.inline-theory summary {
  display: grid; grid-template-columns: 150px 1fr auto; gap: 14px; align-items: center;
  padding: 17px 2px; list-style: none; cursor: pointer;
}
.inline-theory summary::-webkit-details-marker { display: none; }
.inline-theory summary span {
  font: 700 11px var(--sans); letter-spacing: .08em; text-transform: uppercase; color: var(--blue-ink);
}
.inline-theory summary b { font-size: 16.5px; }
.inline-theory summary i { font: 20px var(--sans); font-style: normal; color: var(--muted); }
.inline-theory > div { padding: 3px 18px 18px; border-left: 2px solid var(--blue); }
.inline-theory > div p { font-size: 16px; color: var(--soft); }
.inline-theory mjx-container[display="true"] { overflow-x: auto; overflow-y: hidden; }

/* Paper-native experiment figures. */
.paper-results {
  width: 100%; max-width: var(--content); margin: 30px auto 8px;
  display: grid; grid-template-columns: 1fr 1fr; gap: 30px 22px;
}
.paper-results figure { min-width: 0; margin: 0; }
.paper-results figure a { display: block; border: 1px solid var(--line); border-radius: 8px; background: white; overflow: hidden; }
.paper-results figure img { display: block; width: 100%; height: auto; }
.paper-results figcaption { margin-top: 10px; font: 13px/1.55 var(--sans); color: var(--muted); }
.paper-results figcaption b { color: var(--soft); }
.paper-results__diversity { grid-column: 1 / -1; width: 55%; justify-self: center; }

@media(max-width:760px){
  .inline-theory summary { grid-template-columns: 105px 1fr auto; gap: 8px; }
  .inline-theory summary b { font-size: 15px; }
  .inline-theory > div { padding-inline: 13px; }
  .paper-results { grid-template-columns: 1fr; }
  .paper-results__diversity { grid-column: auto; width: 100%; }
}
/* Two paper figures: acceleration and diversity, aligned at equal width. */
.paper-results { grid-template-columns: 1fr 1fr; align-items: start; }
.paper-results__diversity { grid-column: auto; width: auto; justify-self: stretch; }
@media(max-width:760px){ .paper-results { grid-template-columns: 1fr; } }
/* Benchmark table: centered values, left-aligned identifiers, bold column wins. */
.benchmark-details table th,
.benchmark-details table td { text-align: center; vertical-align: middle; }
.benchmark-details table th:first-child,
.benchmark-details table td:first-child,
.benchmark-details table th:nth-child(2),
.benchmark-details table td:nth-child(2) { text-align: left; }
.benchmark-details table strong { font-weight: 700; color: var(--ink); }
.benchmark-details table tr.ours strong { color: var(--blue-ink); }
/* Rowspans change child indices; align identifier cells by semantic class. */
.benchmark-details table th,
.benchmark-details table td,
.benchmark-details table th:nth-child(2),
.benchmark-details table td:nth-child(2) { text-align: center; }
.benchmark-details table .col-model,
.benchmark-details table .col-method { text-align: left; }
/* Center all method names; only the grouped model label stays left-aligned. */
.benchmark-details table .col-method { text-align: center; }
.benchmark-details table .col-model { text-align: left; }
/* Definitive benchmark alignment — intentionally last in the cascade. */
.benchmark-details table th.col-method,
.benchmark-details table td.col-method {
  text-align: center !important;
  vertical-align: middle !important;
}
.benchmark-details table th.col-model,
.benchmark-details table td.col-model {
  text-align: left !important;
  vertical-align: middle !important;
}
.benchmark-details table th:not(.col-model):not(.col-method),
.benchmark-details table td:not(.col-model):not(.col-method) {
  text-align: center !important;
  vertical-align: middle !important;
}
.benchmark-details td .delta {
  display:block;
  margin-top:2px;
  font:600 10.5px/1.25 var(--mono);
}
.delta--positive { color:var(--gain) !important; }
.delta--negative { color:var(--loss) !important; }
.benchmark-details .baseline { background:color-mix(in srgb,var(--muted) 7%,transparent); }
.benchmark-details .baseline small {
  display:block;
  margin-top:2px;
  font:600 9px/1.2 var(--sans);
  letter-spacing:.05em;
  text-transform:uppercase;
  color:var(--muted);
}
.delta-legend {
  display:flex;
  justify-content:flex-end;
  gap:14px;
  margin:0 0 8px;
  font:600 11px/1.3 var(--sans);
}
.delta-legend .delta { display:inline; }

/* ====================== Diversity analysis ====================== */
.diversity-definition,
.judge-pipeline,
.diversity-paper-figure,
.case-study,
.scope-note {
  width: 100%; max-width: var(--content); margin-left: auto; margin-right: auto;
}
.diversity-definition {
  margin-top: 28px; display: grid; grid-template-columns: .9fr 1.1fr;
  border: 1px solid var(--line); border-radius: 9px; background: var(--surface); overflow: hidden;
}
.diversity-definition > div { padding: 23px; background: var(--blue-wash); }
.diversity-definition > div span { font: 700 11px var(--sans); letter-spacing: .09em; text-transform: uppercase; color: var(--blue-ink); }
.diversity-definition > div mjx-container[display="true"] { margin: 1em 0 .2em !important; }
.diversity-definition > p { margin: 0; padding: 23px; font-size: 16px; line-height: 1.62; color: var(--soft); }

.judge-pipeline {
  margin-top: 18px; display: grid;
  grid-template-columns: 1fr 38px 1fr 38px 1fr 38px 1fr;
  gap: 8px; align-items: center;
}
.judge-pipeline article { min-height: 190px; padding: 19px 17px; border: 1px solid var(--line); border-radius: 8px; background: var(--surface); }
.judge-pipeline article > span { width: 23px; height: 23px; display: grid; place-items: center; border-radius: 50%; border: 1px solid color-mix(in srgb,var(--blue) 42%,var(--line)); font: 700 11px var(--sans); color: var(--blue-ink); }
.judge-pipeline article b { display: block; margin: 14px 0 6px; font-size: 16px; }
.judge-pipeline article p { margin: 0; font: 12.5px/1.52 var(--sans); color: var(--muted); }
.judge-pipeline svg { width: 100%; fill: none; stroke: var(--muted); stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
.protocol-note { margin-top: 14px !important; font: 13px/1.55 var(--sans); color: var(--muted) !important; }

.diversity-paper-figure { margin-top: 34px; text-align: center; }
.diversity-paper-figure a { display: inline-block; width: 55%; border: 1px solid var(--line); border-radius: 8px; overflow: hidden; background: white; }
.diversity-paper-figure img { display: block; width: 100%; height: auto; }
.diversity-paper-figure figcaption { max-width: 620px; margin: 10px auto 0; font: 13px/1.55 var(--sans); color: var(--muted); }
.diversity-paper-figure figcaption b { color: var(--soft); }

.case-study { margin-top: 18px; padding: 24px; border: 1px solid var(--line); border-radius: 9px; background: var(--surface); }
.case-study__problem { padding-bottom: 18px; border-bottom: 1px solid var(--line); font-size: 16px; color: var(--soft); }
.case-study__routes { display: grid; grid-template-columns: 1fr 70px 1fr; gap: 14px; align-items: stretch; }
.case-study__routes article { padding: 20px; background: var(--line2); border-radius: 7px; }
.case-study__routes article > span { font: 700 11px var(--sans); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.case-study__routes h3 { margin: 8px 0 9px; font-size: 19px; }
.case-study__routes p { font-size: 14.5px; line-height: 1.58; color: var(--soft); }
.case-study__routes article > div { display: flex; flex-wrap: wrap; gap: 6px; }
.case-study__routes i { padding: 3px 7px; border: 1px solid var(--line); border-radius: 99px; background: var(--surface); font: 11px var(--sans); font-style: normal; color: var(--muted); }
.case-study__flowbalance { background: var(--blue-wash) !important; }
.case-study__flowbalance > span { color: var(--blue-ink) !important; }
.case-study__vs { display: grid; place-items: center; font: 700 10px var(--sans); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.case-study__point { margin: 18px 0 0; padding-top: 16px; border-top: 1px solid var(--line); font-size: 15px; color: var(--soft); }
.scope-note { margin-top: 24px; padding: 15px 18px; border-left: 2px solid var(--orange); background: var(--orange-wash); font-size: 15px; color: var(--soft); }

@media(max-width:900px){
  .judge-pipeline { grid-template-columns: 1fr; }
  .judge-pipeline article { min-height: 0; }
  .judge-pipeline svg { width: 48px; justify-self: center; transform: rotate(90deg); }
}
@media(max-width:760px){
  .diversity-definition { grid-template-columns: 1fr; }
  .diversity-paper-figure a { width: 100%; }
  .case-study { padding: 18px 15px; }
  .case-study__routes { grid-template-columns: 1fr; }
  .case-study__vs { min-height: 28px; }
}
.paper-overview {
  width: 100%; max-width: var(--content); margin: 42px auto 0;
}
.paper-overview a {
  display: block; border: 1px solid var(--line); border-radius: 8px;
  background: white; overflow: hidden;
}
.paper-overview img { display: block; width: 100%; height: auto; }
.paper-overview figcaption {
  margin-top: 10px; font: 13px/1.55 var(--sans); color: var(--muted);
}
.paper-overview figcaption b { color: var(--soft); }
.diversity-formula {
  width: 100%; max-width: var(--content); margin: 22px auto 28px;
  padding: 18px 22px; border-left: 3px solid var(--blue); background: var(--blue-wash);
}
.diversity-formula mjx-container[display="true"] { margin: .4em 0 .7em !important; }
.diversity-formula p { margin: 0; font-size: 15px; line-height: 1.58; color: var(--soft); }
/* Part labels should read as quiet navigation, not bold headings. */
.section__label { font-weight: 400; }
/* Section titles use the same display face and weight as the FlowBalance title. */
.section h2 {
  font-family: var(--serif);
  font-weight: 600;
}
.definition-label {
  display: block;
  font-family: var(--serif);
  font-size: 17px;
  font-weight: 600;
  color: var(--ink);
}
/* Compact sign-gate cards: horizontal rather than tall icon stacks. */
.gate-rule {
  grid-template-columns: 1fr 86px 1fr;
  gap: 12px;
}
.gate-rule article {
  display: grid;
  grid-template-columns: 40px auto 1fr;
  grid-template-rows: auto auto;
  column-gap: 10px;
  row-gap: 2px;
  align-items: center;
  padding: 14px 16px;
  text-align: left;
}
.gate-rule article > span {
  grid-column: 2;
  grid-row: 1;
  font-size: 12px;
}
.gate-rule svg {
  grid-column: 1;
  grid-row: 1 / 3;
  width: 36px;
  height: 36px;
  margin: 0;
}
.gate-rule h3 {
  grid-column: 3;
  grid-row: 1;
  font-size: 17px;
  white-space: nowrap;
}
.gate-rule p {
  grid-column: 2 / 4;
  grid-row: 2;
  margin: 2px 0 0;
  font-size: 12.5px;
}
.gate-rule__verb { font-size: 10px; }

@media(max-width:760px){
  .gate-rule { grid-template-columns: 1fr; }
  .gate-rule__verb { padding: 7px; }
}
/* Make the advantage sign the primary label in compact gate cards. */
.gate-rule article > span {
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
}

/* Explanation immediately above the probability-mass playground. */
.mass-explainer {
  width: 100%; max-width: var(--content); margin: 18px auto 14px;
  display: grid; grid-template-columns: 1.08fr .92fr;
  border: 1px solid var(--line); border-radius: 9px; background: var(--surface); overflow: hidden;
}
.mass-explainer__formula { padding: 20px 22px; background: var(--blue-wash); }
.mass-explainer__formula mjx-container[display="true"] { margin: .35em 0 .65em !important; }
.mass-explainer__formula > span { font: 12px var(--sans); color: var(--muted); }
.mass-explainer__guide { padding: 17px 20px; }
.mass-explainer__guide p { display: grid; grid-template-columns: 145px 1fr; gap: 10px; margin: 0; padding: 7px 0; border-bottom: 1px solid var(--line2); }
.mass-explainer__guide p:last-child { border-bottom: 0; }
.mass-explainer__guide b { font: 600 12.5px/1.45 var(--sans); color: var(--ink); }
.mass-explainer__guide span { font: 12.5px/1.45 var(--sans); color: var(--muted); }
.experiment-prompt {
  width: 100%; max-width: var(--content); margin: 0 auto 14px;
  padding: 13px 17px; border-left: 2px solid var(--orange); background: var(--orange-wash);
  font-size: 14.5px; line-height: 1.55; color: var(--soft);
}
@media(max-width:760px){
  .mass-explainer { grid-template-columns: 1fr; }
  .mass-explainer__formula { padding: 17px 14px; overflow-x: auto; }
  .mass-explainer__formula mjx-container { font-size: 84% !important; }
  .mass-explainer__guide p { grid-template-columns: 1fr; gap: 2px; }
}
/* Center the toy target equation after removing auxiliary notes. */
.mass-explainer__formula {
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
}
.mass-explainer__formula mjx-container[display="true"] {
  width: 100%;
  text-align: center !important;
}

/* Trajectory Balance narrative: target condition -> residual -> loss -> partition. */
.tb-equation,
.tb-logic,
.tb-partition {
  width: 100%; max-width: var(--content); margin-left: auto; margin-right: auto;
}
.tb-equation {
  margin-top: 18px; margin-bottom: 20px; padding: 19px 22px;
  border-left: 3px solid var(--blue); background: var(--blue-wash); overflow-x: auto;
}
.tb-equation > span,
.tb-partition > span {
  display: block; font: 700 11px var(--sans); letter-spacing: .09em;
  text-transform: uppercase; color: var(--blue-ink);
}
.tb-equation mjx-container[display="true"],
.tb-partition mjx-container[display="true"] { margin: .6em 0 .2em !important; }
.tb-equation--target { background: var(--surface); border: 1px solid var(--line); border-left: 3px solid var(--blue); }
.tb-equation--loss { background: var(--line2); border-left-color: var(--muted); }
.tb-equation--loss > span { color: var(--muted); }
.tb-logic { margin-top: 28px; margin-bottom: 22px; border-top: 1px solid var(--line); }
.tb-logic article {
  display: grid; grid-template-columns: 42px 1fr; gap: 10px;
  padding: 17px 0; border-bottom: 1px solid var(--line);
}
.tb-logic article > span {
  font: 600 12px var(--mono); color: var(--blue-ink);
}
.tb-logic b { font-size: 16px; }
.tb-logic p { margin: 3px 0 0; font-size: 15px; line-height: 1.55; color: var(--soft); }
.tb-partition {
  margin-top: 22px; margin-bottom: 24px; padding: 18px 22px;
  border: 1px solid var(--line); border-radius: 8px; background: var(--surface); overflow-x: auto;
}
@media(max-width:760px){
  .tb-equation,.tb-partition { padding: 16px 13px; }
  .tb-equation mjx-container,.tb-partition mjx-container { font-size: 86% !important; }
}

/* Bilingual segmented switch, following the reference site's compact treatment. */
.lang-switch {
  display: inline-flex; align-items: center; padding: 2px;
  border: 1px solid var(--line); border-radius: 7px; background: var(--line2);
}
.lang-switch a {
  padding: 4px 8px; border-radius: 5px;
  font: 600 11px/1.25 var(--sans); color: var(--muted);
}
.lang-switch a:hover { text-decoration: none; color: var(--ink); }
.lang-switch a.active { background: var(--surface); color: var(--blue-ink); box-shadow: 0 1px 2px color-mix(in srgb,var(--ink) 10%,transparent); }

/* Chinese editorial voice: CJK serif body with slightly more generous leading. */
html[lang="zh-CN"] body {
  font-family: "Noto Serif SC", "Songti SC", "STSong", "Source Han Serif SC", var(--serif);
  line-height: 1.82;
}
html[lang="zh-CN"] h1,
html[lang="zh-CN"] h2,
html[lang="zh-CN"] h3 { line-height: 1.3; letter-spacing: 0; }
html[lang="zh-CN"] .hero__tagline { font-style: normal; }
html[lang="zh-CN"] .eyebrow,
html[lang="zh-CN"] .section__label,
html[lang="zh-CN"] .toc > p,
html[lang="zh-CN"] .tb-equation > span,
html[lang="zh-CN"] .tb-partition > span,
html[lang="zh-CN"] .equation-card > span,
html[lang="zh-CN"] .term-grid span,
html[lang="zh-CN"] .inline-theory summary span,
html[lang="zh-CN"] .case-study__routes article > span { letter-spacing: .045em; }
html[lang="zh-CN"] .section > p,
html[lang="zh-CN"] .hero__lead { line-height: 1.85; }
html[lang="zh-CN"] .topnav,
html[lang="zh-CN"] .toc,
html[lang="zh-CN"] .byline,
html[lang="zh-CN"] .mass-lab,
html[lang="zh-CN"] table,
html[lang="zh-CN"] figcaption { font-family: "Inter", "PingFang SC", "Microsoft YaHei", sans-serif; }
@media(max-width:760px){
  .lang-switch a { padding: 4px 7px; }
}
@media(max-width:760px){
  .topnav { gap: 7px; }
  .topnav__pill { display: none; }
  html[lang="zh-CN"] .hero h1 { font-size: clamp(34px, 9.3vw, 43px); }
  html[lang="zh-CN"] .hero__tagline { font-size: 19px; }
}

/* Expanded motivation: problem definition -> failure case -> distributional bet. */
.motivation-intro{padding-top:70px;scroll-margin-top:72px}
.motivation-intro>h2{margin:9px 0 18px;font-size:clamp(29px,3.8vw,38px);letter-spacing:-.02em}
.motivation-intro>p{color:var(--soft)}
.motivation-equation{margin:18px auto 22px!important;text-align:center}
.motivation-equation mjx-container[display=true]{margin:.35em 0!important}
.motivation-visual__opportunity{border-left-color:var(--blue)!important;background:var(--blue-wash)!important}
.motivation-visual__opportunity span{color:var(--blue-ink)}
.motivation-transition{margin-top:28px!important}
@media(max-width:760px){.motivation-intro{padding-top:58px}.motivation-intro>h2{font-size:30px}}

/* Motivation layout: three narrative cards in one row, figure on its own row. */
.motivation-visual{
  grid-template-columns:1fr;
  align-items:start;
}
.motivation-visual__story{
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:12px;
}
.motivation-visual__story article{
  min-height:190px;
}
.motivation-visual__story article::after{
  display:none;
}
.motivation-figure{
  width:100%;
}
.motivation-figure__link{
  display:flex;
  justify-content:center;
  background:#fff;
}
.motivation-figure img{
  width:100%;
  max-height:430px;
  object-fit:contain;
}
@media(max-width:760px){
  .motivation-visual__story{grid-template-columns:1fr}
  .motivation-visual__story article{min-height:0}
}

/* Place the negative-case figure above the three cards at a readable natural size. */
.motivation-figure{
  order:-1;
  width:100%;
  justify-self:center;
}
.motivation-figure__link{
  display:block;
}
.motivation-figure img{
  width:auto;
  max-width:100%;
  max-height:none;
  margin:0 auto;
  object-fit:initial;
}
@media(max-width:760px){
  .motivation-figure{width:100%}
}

/* Keep the Part 01 title typographically identical to all section titles. */
.section h2,
.motivation-intro > h2 {
  margin:9px auto 18px;
  font-family:var(--serif);
  font-size:clamp(29px,3.8vw,38px);
  font-weight:600;
  line-height:1.16;
  letter-spacing:-.02em;
  color:var(--ink);
}
@media(max-width:760px){
  .section h2,
  .motivation-intro > h2 { font-size:30px; }
}


/* FlowBalance-specific result and overview refinements. */
.paper-overview-inline figcaption { margin-top: 10px; font: 13px/1.55 var(--sans); color: var(--muted); }
.paper-results.paper-results--three { grid-template-columns: repeat(3,minmax(0,1fr)); }
.paper-results.paper-results--three figure { min-width: 0; }
.paper-results.paper-results--three img { width: 100%; height: auto; }
.result-highlights { width:100%; max-width:var(--content); margin:24px auto 22px; display:grid; grid-template-columns:repeat(3,1fr); gap:12px; }
.result-highlights article { padding:18px; border:1px solid var(--line); border-radius:8px; background:var(--surface); }
.result-highlights span { display:block; font:700 11px var(--sans); letter-spacing:.08em; text-transform:uppercase; color:var(--blue-ink); }
.result-highlights b { display:block; margin:7px 0 4px; font:600 29px/1 var(--serif); color:var(--ink); }
.result-highlights p { margin:0; font:12.5px/1.5 var(--sans); color:var(--muted); }
@media(max-width:900px){ .paper-results.paper-results--three { grid-template-columns:1fr 1fr; } .paper-results.paper-results--three figure:last-child { grid-column:1/-1; width:50%; justify-self:center; } }
@media(max-width:760px){ .paper-results.paper-results--three,.result-highlights { grid-template-columns:1fr; } .paper-results.paper-results--three figure:last-child { grid-column:auto; width:auto; } }

.case-intro { margin-top:24px !important; color:var(--soft); }
.case-study + .case-study { margin-top:16px; }


.hero-actions { width:100%; max-width:var(--content); margin:22px auto 4px; display:flex; flex-wrap:wrap; gap:9px; }
.hero-action { display:inline-flex; align-items:center; justify-content:center; min-height:38px; padding:8px 14px; border:1px solid var(--line); border-radius:7px; background:var(--surface); font:600 12px var(--sans); color:var(--soft); }
.hero-action:hover { text-decoration:none; border-color:color-mix(in srgb,var(--blue) 50%,var(--line)); color:var(--blue-ink); }
.hero-action--primary { border-color:var(--blue); background:var(--blue); color:white; }
.hero-action--primary:hover { color:white; filter:brightness(.94); }
@media(max-width:760px){ .hero-actions { margin-top:18px; } }