:root{color-scheme:light;--ink:#263e4b;--muted:#62717a;--line:#d3d9d8;--paper:#fcfbf7;--blue:#315f79;--rust:#9a5947;--gold:#c69b46;font-family:Arial,Helvetica,sans-serif;color:var(--ink);background:var(--paper)}
*{box-sizing:border-box}body{margin:0}button,input{font:inherit}button,a,input{touch-action:manipulation}button{cursor:pointer}button:focus-visible,a:focus-visible,input:focus-visible,canvas:focus-visible,summary:focus-visible{outline:3px solid #a77d2e;outline-offset:4px}button{color:inherit}a{color:inherit;text-underline-offset:4px}button:disabled{cursor:default}button:disabled:not([aria-pressed=true]){opacity:.5}[hidden]{display:none!important}
main{max-width:1260px;margin:0 auto;padding:54px 32px 76px}h1,h2,h3,p,figure{margin:0}h1,h2,h3{font-family:Georgia,'Times New Roman',serif;font-weight:400}h1{font-size:56px;line-height:1.08;letter-spacing:-1.4px}h2{font-size:34px;line-height:1.2}h3{font-size:26px}p{line-height:1.75}strong{font-weight:600}.intro{font-size:18px;margin-top:22px;color:var(--muted)}.topic-title{margin-bottom:32px}.blue{color:var(--blue)}.rust{color:var(--rust)}.math{font-family:Georgia,serif}.small{font-size:14px;color:var(--muted)}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}
.mode-bar{display:flex;flex-wrap:wrap;gap:5px;border-bottom:1px solid var(--line);padding:14px 18px;background:#fff}.mode-bar button,.text-button,.camera-buttons button{border:1px solid transparent;background:none;padding:9px 12px;font-size:14px;line-height:1.3}.mode-bar button:hover,.text-button:hover,.camera-buttons button:hover{background:#edf1f1}.mode-bar button[aria-pressed=true]{background:var(--ink);color:white}.mode-bar .utility{margin-left:auto;display:flex;gap:5px}.studio{border:1px solid var(--line);background:white;overflow:hidden}.studio:fullscreen{width:100%;height:100%;background:var(--paper);display:flex;flex-direction:column;padding:18px}.studio:fullscreen .viewport{flex:1;height:auto;min-height:0}.studio:fullscreen .pair-grid{flex:1;min-height:0}.studio:fullscreen .model-card{display:flex;flex-direction:column;min-height:0}.studio:fullscreen .paired-names{flex:0 0 auto}
.viewport{height:405px;position:relative;isolation:isolate;min-width:0;background:radial-gradient(ellipse at 50% 65%,#f5f6f2 0%,#fdfdfb 66%)}.viewport canvas{display:block;width:100%;height:100%;position:relative;z-index:1;touch-action:none}.view-fallback{position:absolute;inset:0;width:100%;height:100%;object-fit:contain;padding:20px}.viewport.ready>.view-fallback{visibility:hidden}.paired-viewport{height:500px;display:grid;grid-template-columns:1fr 1fr}.viewport.linked-pane{height:100%;min-height:0;background:transparent}.view-help{padding:11px 18px;color:var(--muted);font-size:12px;border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap}.camera-buttons{display:flex;gap:4px}.camera-buttons button{padding:0 5px;font-size:12px}.pair-grid{display:grid;grid-template-columns:1fr 1fr}.model-card+ .model-card{border-left:1px solid var(--line)}.model-card h2{padding:24px 28px 0;font-size:31px}.model-card .shape-description{font-size:15px;margin:9px 28px 0;color:var(--muted)}.count-row{display:flex;flex-wrap:wrap;gap:22px;padding:13px 28px;border-top:1px solid var(--line);font-size:14px}.count-row b{font-family:Georgia,serif;font-size:22px;margin-right:4px}.model-card .shape-result{display:flex;justify-content:space-between;align-items:end;padding:20px 28px 24px;background:#f0f5f7}.model-card.pyramid .shape-result{background:#f8eeea}.shape-result .answer{font:43px Georgia,serif;line-height:1.1}.shape-result .answer small{font:15px Arial}.shape-result .formula{font:21px Georgia,serif}.shape-result .measure-name{display:block;font-size:13px;margin-bottom:7px}
.dimensions{border-top:2px solid var(--ink);margin-top:34px;padding-top:24px}.dimensions-heading{display:flex;justify-content:space-between;align-items:baseline;gap:22px;margin-bottom:20px}.dimensions-heading h2{font-size:29px}.input-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:28px}.dimension label{display:block;font-size:14px;margin-bottom:12px}.dimension label i{font:italic 19px Georgia,serif}.dimension .input-line{display:flex;align-items:center;gap:15px}.dimension input[type=range]{accent-color:var(--blue);width:100%;min-width:0;height:30px}.dimension input[type=number]{width:74px;background:white;border:1px solid #aebcc3;padding:10px;font-size:17px;color:var(--ink)}input[aria-invalid=true]{outline:2px solid #aa493b}.dimensions .footnote{margin-top:18px;font-size:13px;color:var(--muted)}.triangle-key{margin-top:22px;display:flex;gap:22px;align-items:center;background:#f1efe7;padding:18px 24px}.triangle-key svg{flex:0 0 150px;width:150px;height:100px}.triangle-key p{font-size:14px}.triangle-key .base-number{font:29px Georgia,serif;white-space:nowrap;margin-left:auto}
.mode-adjust{padding:20px 28px;background:#f6f4ed;border-top:1px solid var(--line)}.slider-label{display:flex;justify-content:space-between;gap:12px;align-items:baseline;font-size:15px}.mode-adjust input{width:100%;accent-color:var(--ink);margin:13px 0 0}.range-ends{display:flex;justify-content:space-between;font-size:12px;color:var(--muted);margin-top:2px}.comparison-table{margin-top:55px}.comparison-table h2{margin-bottom:24px}.table-wrap{overflow-x:auto}table{border-collapse:collapse;width:100%;font-size:16px}th,td{text-align:left;vertical-align:top;border-bottom:1px solid var(--line);padding:18px 20px}thead th{background:#eef3f4;font-size:15px}thead th:last-child{background:#f5ede8}tbody th{font-weight:400;width:26%;color:var(--muted)}td b{font-weight:600}caption{text-align:left;font-size:14px;color:var(--muted);padding:0 0 12px}td .math{font-size:21px}.definition-note{border-left:3px solid var(--gold);padding:4px 0 4px 22px;margin-top:28px}.definition-note p{font-size:16px}.definition-note h3{font-size:25px;margin-bottom:8px}
.featured{margin-top:60px;padding-top:32px;border-top:2px solid var(--ink);display:grid;grid-template-columns:270px 1fr;gap:38px;align-items:center}.featured img{display:block;width:100%;height:auto;border:1px solid var(--line)}.featured h2{margin-bottom:14px}.featured p{font-size:16px}.pin-actions{display:flex;gap:20px;align-items:center;margin-top:24px;font-size:14px}.pin-it{display:inline-block;background:#a22a2d;color:white;text-decoration:none;padding:8px 15px;border-radius:3px}.featured figcaption{font-size:12px;margin-top:8px;color:var(--muted)}.questions{margin-top:40px;display:grid;grid-template-columns:1fr 1fr;gap:28px}.questions details{border-top:1px solid var(--line);padding-top:16px}.questions summary{cursor:pointer;font:22px/1.35 Georgia,serif}.questions p{margin-top:15px;font-size:15px}.noscript{padding:18px;border:1px solid var(--line);margin:20px 0}
/* Design 2: a shared experiment, with the measurements in a narrow ledger. */
.design-2{--paper:#f7f4ec;--ink:#393b34;--blue:#466d7d}.design-2 main{max-width:1360px}.design-2 h1{font-size:58px}.experiment-intro{display:grid;grid-template-columns:1.2fr 1fr;gap:50px;align-items:end;margin-top:24px;margin-bottom:30px}.experiment-intro h2{font-size:37px;line-height:1.22}.experiment-intro p{font-size:17px;color:var(--muted)}.experiment{display:grid;grid-template-columns:minmax(0,1fr) 275px;gap:0;border:1px solid #c9c9bc;background:#fff}.experiment .studio{border:0;border-right:1px solid #c9c9bc}.paired-names{display:grid;grid-template-columns:1fr 1fr;text-align:center;padding:24px 20px 0;gap:20px}.paired-names h3{font-size:25px}.paired-names p{font-size:13px;color:var(--muted);margin-top:5px}.experiment .paired-viewport{height:425px;background:radial-gradient(ellipse at center,#f6f1e5,#fffefa)}.experiment-ledger{padding:24px 25px;background:#f1ede1;display:flex;flex-direction:column}.experiment-ledger h2{font-size:27px;margin-bottom:18px}.experiment-ledger .volume{padding:18px 0;border-top:1px solid #cbcbbd}.volume .label{font-size:14px}.volume strong{display:block;font:43px Georgia,serif;margin-top:8px}.volume .math{display:block;margin-top:8px;font-size:20px}.ratio{margin-top:auto;padding-top:25px}.ratio strong{font:56px Georgia,serif;letter-spacing:1px}.ratio p{font-size:13px;margin-top:7px}.ratio-blocks{display:flex;gap:5px;margin:16px 0 7px}.ratio-blocks span{height:16px;flex:1;background:#8bafbf}.ratio-blocks.single span{background:#c1907c;flex:0 0 calc((100% - 10px)/3)}.slice-results{display:grid;grid-template-columns:1fr 1fr;gap:35px;padding:22px 28px;background:#fffefa}.slice-results p{font-size:14px}.slice-results strong{font:32px Georgia,serif}.slice-results .bar-track{height:8px;background:#ece5d4;margin-top:12px}.slice-results .bar{height:100%;background:var(--gold)}.experiment .mode-adjust{background:#f1ede1}.why-third{display:grid;grid-template-columns:.75fr 1fr;gap:48px;margin-top:42px;padding:32px 0;border-top:1px solid #bcbfaf;border-bottom:1px solid #bcbfaf}.why-third .large-fraction{font:72px Georgia,serif;color:var(--rust)}.why-third p{font-size:16px}.why-third h2{margin-bottom:15px}.design-2 .dimensions{margin-top:40px}.design-2 .featured{grid-template-columns:1fr 270px}.design-2 .featured figure{grid-column:2;grid-row:1}.design-2 .featured .featured-copy{grid-column:1;grid-row:1}
/* Design 3: a face atlas with a side index and an open drawing field. */
.design-3{--paper:#fff;--ink:#31444b;--blue:#356c82}.design-3 h1{font-size:53px}.design-3 .intro{font-size:18px}.atlas{display:grid;grid-template-columns:252px minmax(0,1fr);border-top:3px solid var(--ink);border-bottom:1px solid var(--line);background:#f4f7f5}.atlas-index{padding:25px 24px 24px 0;background:#fff}.atlas-index h2{font-size:25px;margin-bottom:22px}.atlas-index .steps{display:flex;flex-direction:column;gap:8px}.steps button{display:flex;text-align:left;align-items:center;gap:15px;border:1px solid var(--line);background:#fff;padding:15px 14px;font-size:15px}.steps button[aria-pressed=true]{background:#e5eef0;border-color:#62818b;font-weight:600}.steps button span{font:25px Georgia,serif;color:var(--blue)}.atlas-index .explanation{margin-top:26px;font-size:14px;line-height:1.7}.atlas .studio{border:0;background:transparent}.atlas .mode-bar{justify-content:flex-end;background:#f4f7f5}.atlas .paired-viewport{height:430px;background:radial-gradient(ellipse at center,#edf1eb,#f4f7f5)}.atlas .paired-names h3{font-size:24px}.atlas-counts{display:grid;grid-template-columns:1fr 1fr;gap:36px;padding:22px 28px}.atlas-counts .counts{display:flex;gap:23px;justify-content:center}.atlas-counts b{font:27px Georgia,serif;display:block}.atlas-counts span{font-size:12px;text-align:center}.face-inventory{display:grid;grid-template-columns:1fr 1fr;gap:44px;margin-top:35px}.face-inventory h2{font-size:28px;padding-bottom:18px;border-bottom:1px solid var(--line)}.face-list{display:flex;align-items:center;gap:15px;padding:22px 0}.face-icon{width:42px;height:39px;flex:0 0 42px}.face-list p{font-size:16px}.face-list strong{font:28px Georgia,serif}.face-inventory .face-equation{font:24px Georgia,serif;padding:17px 0;border-top:1px solid var(--line)}.design-3 .comparison-table{margin-top:40px}.design-3 .featured{background:#eff3f0;border-top:0;padding:32px;grid-template-columns:250px 1fr}.design-3 .dimensions{margin-top:38px}
@media(prefers-reduced-motion:no-preference){button,a{transition:background-color .15s,color .15s}.bar{transition:width .12s}}
@media(max-width:1000px){main{padding:38px 24px 55px}h1,.design-2 h1,.design-3 h1{font-size:47px}.viewport{height:345px}.model-card h2{font-size:27px;padding:20px 20px 0}.model-card .shape-description{margin-left:20px;margin-right:20px}.shape-result .answer{font-size:35px}.model-card .shape-result{padding:18px 20px;gap:12px}.count-row{padding:12px 20px;gap:14px}.experiment{grid-template-columns:minmax(0,1fr) 220px}.experiment-ledger{padding:22px 18px}.experiment .paired-viewport{height:380px}.atlas{grid-template-columns:215px minmax(0,1fr)}.atlas-index{padding-right:18px}.atlas .paired-viewport{height:390px}.paired-names h3,.atlas .paired-names h3{font-size:22px}.input-grid{gap:20px}.featured{gap:26px}}
@media(max-width:740px){main{padding:30px 17px 46px}h1,.design-2 h1,.design-3 h1{font-size:39px;letter-spacing:-.8px}h2{font-size:29px}.intro{font-size:16px}.topic-title{margin-bottom:25px}.pair-grid{grid-template-columns:1fr}.model-card+.model-card{border-left:0;border-top:2px solid var(--line)}.viewport{height:330px}.model-card h2{font-size:29px}.count-row{justify-content:space-between}.shape-result .answer{font-size:39px}.mode-bar{padding:10px 12px}.mode-bar .utility{margin-left:0}.mode-bar button{font-size:13px;padding:8px 10px}.dimensions-heading{display:block}.dimensions-heading p{margin-top:10px}.input-grid{grid-template-columns:1fr;gap:21px}.dimension label{margin-bottom:6px}.dimension .input-line{gap:24px}.triangle-key{flex-wrap:wrap;padding:17px;gap:14px}.triangle-key p{flex:1;min-width:160px}.triangle-key .base-number{margin-left:0;font-size:25px}.comparison-table{margin-top:36px}th,td{padding:14px 11px;font-size:14px}td .math{font-size:18px}tbody th{width:27%}.featured,.design-2 .featured,.design-3 .featured{grid-template-columns:1fr;padding:25px 0 0;gap:25px;margin-top:40px}.featured figure,.design-2 .featured figure{grid-column:1;grid-row:2;max-width:330px}.featured .featured-copy,.design-2 .featured .featured-copy{grid-column:1;grid-row:1}.questions{grid-template-columns:1fr;gap:20px}.experiment-intro{grid-template-columns:1fr;gap:18px;margin-top:22px}.experiment-intro h2{font-size:31px}.experiment{grid-template-columns:1fr}.experiment .studio{border-right:0}.experiment-ledger{display:grid;grid-template-columns:1fr 1fr;gap:0 25px;border-top:1px solid var(--line)}.experiment-ledger h2{grid-column:1/-1;font-size:25px}.experiment-ledger .ratio{grid-column:1/-1;display:grid;grid-template-columns:100px 1fr;align-items:center;gap:12px;border-top:1px solid #cbcbbd;padding-top:14px}.ratio p{margin-top:0}.ratio .ratio-bars{display:none}.experiment .paired-viewport{height:335px}.paired-names{gap:12px;padding:20px 12px 0}.paired-names h3{font-size:21px}.paired-names p{font-size:12px}.slice-results{gap:22px;padding:20px}.slice-results strong{font-size:29px}.mode-adjust{padding:18px 20px}.why-third{grid-template-columns:1fr;gap:13px;margin-top:30px;padding:24px 0}.why-third .large-fraction{font-size:55px}.atlas{grid-template-columns:1fr}.atlas-index{padding:20px 0;background:white}.atlas-index h2{margin-bottom:14px}.atlas-index .steps{display:grid;grid-template-columns:1fr 1fr;gap:8px}.steps button{padding:12px;font-size:14px}.steps button span{font-size:22px}.atlas-index .explanation{margin-top:16px;min-height:48px}.atlas .paired-viewport{height:335px}.atlas-counts{padding:18px 12px;gap:20px}.atlas-counts .counts{gap:18px}.face-inventory{gap:24px;margin-top:28px}.face-inventory h2{font-size:23px}.face-list{gap:11px;align-items:start}.face-list p{font-size:14px}.face-list strong{font-size:24px}.face-icon{width:30px;height:30px;flex-basis:30px}.face-inventory .face-equation{font-size:20px}.design-3 .featured{background:none}.studio:fullscreen{padding:0}.studio:fullscreen .pair-grid{grid-template-columns:1fr 1fr}.studio:fullscreen .model-card+.model-card{border-top:0;border-left:1px solid var(--line)}.studio:fullscreen .count-row,.studio:fullscreen .shape-description,.studio:fullscreen .shape-result{display:none}.studio:fullscreen .model-card h2{font-size:20px}}
@media(max-width:390px){h1,.design-2 h1,.design-3 h1{font-size:34px}main{padding-left:14px;padding-right:14px}.viewport{height:305px}.paired-names h3,.atlas .paired-names h3{font-size:19px}.paired-viewport,.atlas .paired-viewport,.experiment .paired-viewport{height:300px}.mode-bar button{padding:7px}.face-inventory{grid-template-columns:1fr}.face-inventory>div+div{margin-top:5px}.atlas-counts .counts{gap:12px}th,td{padding:12px 8px;font-size:13px}}

/* Model-specific controls and the linked-camera switch. */
.mode-bar .utility{flex-wrap:wrap;align-items:center}
.rotation-link{display:inline-flex;align-items:center;gap:8px;padding:8px 10px;min-height:40px;font-size:14px;cursor:pointer;border:1px solid var(--line);background:#f6f7f3}
.rotation-link input{width:18px;height:18px;accent-color:var(--blue);margin:0}
.model-tools{display:flex;flex-wrap:wrap;justify-content:center;gap:4px;padding:14px 8px 4px}
.model-tools button{border:1px solid var(--line);background:transparent;padding:8px 12px;min-height:36px;font-size:13px;line-height:1.2}
.model-tools button[aria-pressed=true]{background:var(--ink);border-color:var(--ink);color:white}
.model-tools button:hover{border-color:var(--ink)}
.model-pane{min-width:0}.model-pane+.model-pane{border-left:1px solid var(--line)}
.experiment .paired-viewport,.atlas .paired-viewport{height:auto;align-items:start}
.paired-viewport .viewport{height:390px;background:transparent}
.local-fold{padding:14px 18px 18px;border-top:1px solid var(--line);background:#fffdf8}
.local-fold label{display:flex;justify-content:space-between;flex-wrap:wrap;gap:4px 12px;font-size:13px;line-height:1.5;margin-bottom:10px}
.local-fold label span{font-size:12px;color:var(--muted)}
.local-fold input{width:100%;min-height:24px;accent-color:var(--blue)}
/* Measurement worksheets show how the colored faces add up. */
.calculation-details{margin-top:42px;border-top:2px solid var(--ink);padding-top:28px}
.calculation-details>p{margin-top:15px}.base-explainer{display:grid;grid-template-columns:130px minmax(0,1fr) auto;align-items:center;gap:25px;padding:26px 22px;background:#f5efdf;margin-top:25px}
.base-explainer>svg{width:100%;height:auto}.base-explainer h3{font-size:25px}.base-explainer p{font-size:14px}.base-explainer .calculation-line{font:26px/1.6 Georgia,serif;margin:5px 0}.calculation-line small{font:14px Arial}
.base-actions{display:flex;flex-direction:column;gap:10px}.base-actions button,.model-action{border:1px solid #a4b1b4;background:white;font-size:13px;padding:11px 13px;min-height:42px;text-align:left;color:var(--ink)}
.base-actions button:hover,.model-action:hover{background:#edf1f1}.base-actions button[aria-pressed=true],.model-action[aria-pressed=true]{border-color:var(--ink);box-shadow:inset 3px 0 var(--ink)}
.calculation-pair{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);margin:25px 0 18px;border:1px solid var(--line)}
.calculation-pair>article{padding:27px;min-width:0}.calculation-pair>article+article{border-left:1px solid var(--line)}
.calculation-pair h3{font-size:27px;line-height:1.25}.calculation-answer{margin-top:23px;padding:22px;background:#edf3f6}.pyramid-calculation .calculation-answer{background:#f8eeea}
.calculation-answer>span,.area-answer>span{font-size:14px;display:block}.calculation-answer>strong,.area-answer>strong{display:block;font:42px/1.3 Georgia,serif;margin:4px 0}.calculation-answer small,.area-answer small{font:14px Arial}.calculation-answer p{font-size:21px}
.area-answer{padding:24px 0 18px}.area-answer>strong{font-size:36px}.area-answer p{font-size:23px}
.face-sum{border-top:1px solid var(--line)}.face-sum>div{display:grid;grid-template-columns:28px minmax(0,1fr) auto;gap:11px;align-items:center;padding:15px 0;border-bottom:1px solid var(--line);font-size:14px;line-height:1.5}
.face-sum b{font-weight:500;text-align:right}.face-sum small{font-size:11px}.face-swatch{display:block;width:25px;height:24px}.face-swatch.triangle{clip-path:polygon(50% 0,100% 100%,0 100%)}.face-swatch.rectangle{height:19px}.gold{background:#e0bd72}.blue-face{background:#80aabd}.pale-blue{background:#527d95}.rust-face{background:#bd806a}.pale-rust{background:#d5a28b}
.lateral-total{display:flex;flex-wrap:wrap;align-items:baseline;gap:7px 13px;margin:18px 0;font-size:14px}.lateral-total strong{font:24px Georgia,serif;margin-left:auto}.lateral-total small{font:12px Arial}.calculation-pair .small{font-size:13px}.model-action{margin-top:20px}.slant-detail{margin-top:16px;font-size:13px;border:0;padding:0}.slant-detail summary{cursor:pointer;font-weight:600}.slant-detail p{margin-top:10px}
.studio:fullscreen .paired-viewport{flex:1;min-height:0;align-items:stretch}.studio:fullscreen .model-pane{display:flex;flex-direction:column;min-height:0}
@media(max-width:1000px){.base-explainer{grid-template-columns:110px minmax(0,1fr)}.base-actions{grid-column:1/-1;flex-direction:row;flex-wrap:wrap}.calculation-pair>article{padding:20px}.paired-viewport .viewport{height:340px}}
@media(max-width:740px){.mode-bar .utility{width:100%;border-top:1px solid var(--line);padding-top:8px;margin-top:5px}.rotation-link{font-size:13px;padding:7px}.model-tools{gap:3px;padding:12px 5px 4px}.model-tools button{padding:8px 6px;font-size:12px}.paired-viewport .viewport{height:285px}.local-fold{padding:12px 10px}.local-fold label{font-size:12px}.base-explainer{grid-template-columns:80px minmax(0,1fr);padding:18px 14px;gap:15px}.base-explainer h3{font-size:23px}.base-explainer .calculation-line{font-size:22px}.base-actions button{flex:1;min-width:120px}.calculation-pair{grid-template-columns:1fr}.calculation-pair>article{padding:22px 18px}.calculation-pair>article+article{border-left:0;border-top:1px solid var(--line)}.calculation-pair h3{font-size:27px}.calculation-answer>strong{font-size:42px}.face-sum>div{gap:9px;font-size:13px}.calculation-details{margin-top:32px}.studio:fullscreen .paired-viewport .viewport{height:auto}}

/* The comparison includes each complete flat net without opening a model mode. */
.net-row th,.net-row td{vertical-align:middle}
.net-note{display:block;margin-top:8px;font-size:12px;line-height:1.5}
.table-net{margin:0;text-align:center}
.table-net .net-diagram{display:block;width:100%;height:auto;max-width:430px;margin:0 auto;background:#fffdf8}
.table-net figcaption{font-size:13px;line-height:1.5;margin-top:10px;color:var(--muted)}
@media(max-width:740px){.net-row td{padding:14px 5px}.net-row th{padding-right:8px}.net-note{font-size:11px}.table-net figcaption{font-size:11px;margin-top:6px}}

/* A single, restrained opening keeps the models close to the title. */
.topic-title{margin-bottom:28px}
.topic-title h1{font-size:clamp(32px,3.9vw,48px);line-height:1.18;letter-spacing:-.7px;text-wrap:balance;font-weight:400}
.topic-title .intro{font-size:17px;line-height:1.7;margin-top:15px;color:#53636c}
.topic-title .intro strong{color:var(--ink);font-weight:600}
.mode-options{display:flex;flex-wrap:wrap;gap:4px;min-width:0;max-width:100%}
.model-pane-heading,.model-pane-counts{display:none}
.mode-bar button,.model-tools button,.camera-buttons button{min-height:44px}
.mode-options button{white-space:nowrap}
main,section,article,aside{min-width:0}
@media(max-width:740px){
 main{padding:25px 16px 44px}
 .topic-title{margin-bottom:22px}
 .topic-title h1{font-size:clamp(30px,7.8vw,39px);line-height:1.2;letter-spacing:-.45px;text-wrap:pretty}
 .topic-title .intro{font-size:16px;line-height:1.65;margin-top:13px}
 .mode-bar{display:block;padding:8px 10px}
 .mode-options{flex-wrap:nowrap;overflow-x:auto;overscroll-behavior-x:contain;scrollbar-width:thin;padding:0 0 5px;gap:4px}
 .mode-options button{flex:0 0 auto;padding:10px 13px;font-size:14px}
 .mode-bar .utility{display:grid;grid-template-columns:1.25fr 1fr 1fr;gap:4px;width:100%;margin:6px 0 0;padding-top:8px}
 .utility button{font-size:13px;padding:8px 4px}
 .rotation-link{font-size:13px;line-height:1.3;min-height:44px;padding:6px;gap:6px}
 .rotation-link input{flex:0 0 18px}
 .paired-names{display:none}
 .experiment .paired-viewport,.atlas .paired-viewport{display:grid;grid-template-columns:minmax(0,1fr);height:auto}
 .model-pane-heading{display:block;text-align:left;font-size:27px;line-height:1.25;padding:21px 20px 0}
 .model-pane+.model-pane{border-left:0;border-top:1px solid var(--line)}
 .paired-viewport .model-pane .viewport{height:clamp(280px,80vw,380px)}
 .model-tools{justify-content:flex-start;padding:14px 20px 0;gap:7px}
 .model-tools button{min-width:68px;min-height:44px;padding:10px 13px;font-size:14px}
 .model-pane-counts{display:flex;justify-content:space-between;gap:12px;padding:13px 20px 18px;font-size:13px;line-height:1.4}
 .model-pane-counts b{font:22px Georgia,serif;margin-right:3px}
 .atlas-counts{display:none}
 .view-help{padding:12px 15px;gap:8px}
 .view-help>span{font-size:12px;line-height:1.6}
 .camera-buttons{width:100%;display:grid;grid-template-columns:repeat(3,1fr);gap:5px}
 .camera-buttons button{font-size:13px;min-height:44px;border:1px solid var(--line);padding:8px}
 .local-fold{padding:15px 20px}.local-fold label{font-size:14px}.local-fold input{min-height:36px}
 .dimension input[type=range]{height:44px}.mode-adjust input{min-height:32px}
 .slider-label{flex-wrap:wrap;gap:5px}.triangle-key .base-number{white-space:normal}
 .experiment-ledger{gap:0 18px;padding:22px 20px}.experiment-ledger h2{font-size:25px}.experiment-ledger .volume strong{font-size:34px}.experiment-ledger .volume small{font-size:13px}
 .why-third .large-fraction{font-size:clamp(31px,9vw,48px)}
 .atlas-index .steps{gap:7px}.steps button{min-height:48px;padding:10px;font-size:13px;line-height:1.4}.steps button span{display:none}
 .table-wrap{overflow:visible}.comparison-table table{display:block}
 .comparison-table caption{display:block;line-height:1.5;margin-bottom:10px}
 .comparison-table thead{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}
 .comparison-table tbody{display:block;border:1px solid var(--line)}
 .comparison-table tbody tr{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr)}
 .comparison-table tbody th{grid-column:1/-1;width:auto;display:block;padding:10px 14px;background:#f0f1eb;color:var(--ink);font-size:14px;font-weight:600;border-bottom:1px solid var(--line)}
 .comparison-table td{display:block;min-width:0;padding:13px 12px;line-height:1.6;font-size:14px;overflow-wrap:anywhere}
 .comparison-table td+td{border-left:1px solid var(--line)}
 .comparison-table td::before{content:attr(data-shape);display:block;font-size:12px;font-weight:600;color:var(--blue);line-height:1.4;margin-bottom:9px}
 .comparison-table td+td::before{color:var(--rust)}
 .comparison-table td .math{font-size:19px}.comparison-table .net-note{display:inline;font-weight:400;margin-left:8px;font-size:12px}
 .comparison-table .net-row td{padding:13px 8px}.table-net figcaption{font-size:12px}
 .featured figure,.design-2 .featured figure{width:min(100%,330px);margin-inline:auto}
 .studio:fullscreen{overflow:auto;display:block}
 .studio:fullscreen .paired-viewport{grid-template-columns:1fr 1fr;align-items:stretch}
 .studio:fullscreen .model-pane+.model-pane{border-left:1px solid var(--line);border-top:0}
 .studio:fullscreen .model-pane-heading{font-size:19px;padding:16px 8px 0}
 .studio:fullscreen .model-tools{padding:10px 5px;gap:3px}
 .studio:fullscreen .model-tools button{min-width:0;padding:7px 6px;font-size:12px}
 .studio:fullscreen .paired-viewport .model-pane .viewport{height:55vh;min-height:240px;flex:none}
 .studio:fullscreen .model-pane-counts{display:none}
}

/* Keep camera actions distinct from the shape-view tabs. */
.mode-bar{display:block;padding:0;background:#fff}
.mode-options{padding:10px 14px}
.mode-bar .utility{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:14px 22px;width:100%;margin:0;padding:13px 18px;border-top:1px solid var(--line);background:#f4f6f3}
.mode-bar>.utility:only-child{border-top:0}
.rotation-link{position:relative;display:inline-flex;align-items:center;gap:11px;min-height:46px;padding:0;border:0;background:transparent;font-size:14px;cursor:pointer;max-width:100%}
.rotation-link input{position:absolute;opacity:0;width:1px;height:1px;margin:0;clip-path:inset(50%)}
.switch-track{display:block;position:relative;flex:0 0 42px;width:42px;height:26px;border:1px solid #87969b;border-radius:14px;background:#e1e6e5}
.switch-track::after{content:"";position:absolute;top:3px;left:3px;width:18px;height:18px;border-radius:50%;background:#fff;border:1px solid #9da8ac}
.rotation-link input:checked+.switch-track{background:var(--blue);border-color:var(--blue)}
.rotation-link input:checked+.switch-track::after{transform:translateX(16px);border-color:#fff}
.rotation-link input:focus-visible+.switch-track{outline:3px solid #a77d2e;outline-offset:4px}
.switch-copy{display:block;line-height:1.4}.switch-copy strong{display:block;font-weight:600;font-size:14px;color:var(--ink)}
.switch-copy small{display:block;font-size:12px;color:var(--muted);margin-top:3px}
.view-actions{display:flex;align-items:center;flex-wrap:wrap;gap:9px}
.mode-bar .view-action{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:44px;padding:10px 14px;border:1px solid #aebbc0;border-radius:4px;font-size:14px;font-weight:500;background:#fff;color:var(--ink);white-space:nowrap;line-height:1.3}
.view-action svg{flex:0 0 18px;display:block}
.mode-bar .reset-action:hover{background:#e8eeec;border-color:#718790}
.mode-bar .fullscreen-action{background:var(--blue);border-color:var(--blue);color:white}
.mode-bar .fullscreen-action:hover{background:#284e64;border-color:#284e64}
.mode-bar .fullscreen-action[aria-pressed=true]{background:#284e64;color:white}
@media(prefers-reduced-motion:no-preference){.switch-track,.switch-track::after{transition:background-color .15s,transform .15s}}
@media(max-width:740px){
 .mode-bar{padding:0}
 .mode-options{padding:8px 10px}
 .mode-bar .utility{display:grid;grid-template-columns:minmax(0,1fr);gap:12px;padding:12px 15px;margin:0}
 .rotation-link{min-height:44px;padding:0;gap:11px}
 .switch-copy strong{font-size:14px}.switch-copy small{font-size:12px}
 .view-actions{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:9px;width:100%}
 .mode-bar .view-action{width:100%;min-height:46px;padding:10px 9px;font-size:14px;gap:8px}
}