@font-face{font-family:'Course Math';src:url('../shapley/fonts/STIXTwoMath-Regular.ttf') format('truetype');font-display:swap}
:root{--ink:#242424;--blue:#234e70;--rust:#a54f32;--teal:#007f73;--muted:#606060;--rule:#767676;--light-rule:#ddd;--paper:#fff;--sans:system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;--serif:Georgia,'Times New Roman',serif;color-scheme:light}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:74px}
body{margin:0;background:var(--paper);color:var(--ink);font:1.125rem/1.65 var(--serif)}
a{color:var(--blue);text-underline-offset:.2em}
button,input,select{font:inherit}
button,select{min-height:42px;border:1px solid var(--rule);background:#fff;color:var(--ink);border-radius:3px;padding:.4rem .8rem}
button{cursor:pointer}button:hover{background:#f1f5f7}button:disabled{opacity:.4;cursor:default}
a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid var(--blue);outline-offset:4px}
[hidden]{display:none!important}
h1,h2,h3{font-weight:400;line-height:1.14;letter-spacing:-.025em}
p{margin:0 0 1.2em}.math,math{font-family:'Course Math','Cambria Math',math}sub,sup{line-height:0}
.quiet{color:var(--muted);font-size:1rem}.equation{font-size:1.5rem;line-height:1.6;margin:1.2em 0}
.skip-link{position:fixed;left:12px;top:-100px;padding:10px;background:white;z-index:100}.skip-link:focus{top:8px}
.masthead{height:64px;padding:0 4vw;display:flex;align-items:center;justify-content:space-between;gap:16px;border-bottom:1px solid var(--light-rule);position:sticky;top:0;background:#fff;z-index:40;font:14px/1.3 var(--sans)}
.masthead>a{text-decoration:none;color:var(--ink);white-space:nowrap}.masthead nav{display:flex;gap:24px}.masthead nav a{text-decoration:none;white-space:nowrap}
.reading-progress{position:fixed;top:63px;left:0;right:0;height:2px;z-index:41}.reading-progress span{display:block;width:0;height:100%;background:var(--blue)}
.title-page{min-height:calc(100svh - 64px);padding:40px 24px 46px;display:grid;place-items:center;text-align:center}.title-content{max-width:1000px;width:100%}
.eyebrow{font:12px/1.5 var(--sans);letter-spacing:.13em;color:var(--muted);margin:0 0 18px}.title-page h1{font-size:clamp(42px,5vw,70px);line-height:1.05;margin:0 0 15px;letter-spacing:-.035em}
.title-subtitle{font-size:clamp(18px,2vw,23px);margin:0 0 10px;color:var(--muted)}.title-art{display:block;width:auto;max-width:min(630px,100%);height:auto;max-height:37svh;object-fit:contain;margin:20px auto 8px}
.start-link{display:inline-flex;align-items:center;min-height:44px;margin-top:10px;font:15px/1.5 var(--sans);padding:6px}
.story-layout{max-width:1500px;margin:auto;padding:0 4vw}
.stage-shell{position:sticky;top:64px;height:72svh;min-height:500px;display:grid;grid-template-columns:minmax(0,1fr) 280px;grid-template-rows:auto minmax(0,1fr) auto;column-gap:24px;row-gap:10px;min-width:0;padding:14px 0 10px;background:#fff;z-index:20;border-bottom:1px solid var(--light-rule)}
.stage-top{display:flex;justify-content:space-between;gap:16px;font:13px/1.5 var(--sans);color:var(--muted);padding-bottom:10px;border-bottom:1px solid var(--light-rule)}
#stage-count{flex-shrink:0;white-space:nowrap}
.visual-area{grid-column:1;grid-row:2;position:relative;min-width:0;min-height:0;display:flex;align-items:center;justify-content:center;isolation:isolate}.worked-diagram{width:100%;height:100%;min-width:0}
.vector-readout{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;min-height:55px;padding:12px 0;border-top:1px solid var(--light-rule);font:14px/1.5 var(--sans);font-variant-numeric:tabular-nums}
.vector-readout>div{min-width:0}.vector-readout .value{display:block;font-family:'Course Math',math;font-size:20px;color:var(--ink);overflow-wrap:anywhere}.vector-readout .readout-label{font-size:12px;color:var(--muted)}
.stage-caption{font:14px/1.5 var(--sans);color:var(--muted);min-height:44px;margin:12px 0}
.stage-nav{display:flex;align-items:center;justify-content:space-between;gap:12px;padding-top:12px;border-top:1px solid var(--light-rule);font:13px/1.4 var(--sans)}.stage-nav span{color:var(--muted);text-align:center;font-size:12px}.stage-nav button{font:14px/1.4 var(--sans);min-width:78px}
.narrative{min-width:0}.step{min-height:90svh;display:flex;align-items:flex-start;padding:30px 0 50px}.step>div{max-width:840px;width:100%;margin:0 auto}.step h2{font-size:clamp(24px,2.1vw,29px);margin:0 0 12px}.step-number{font:12px/1.5 var(--sans);letter-spacing:.08em;color:var(--blue);margin-bottom:10px}.step p{line-height:1.55;margin:0 0 14px}
.controls{font:14px/1.5 var(--sans);padding:8px 0;border-top:1px solid var(--light-rule)}.worked-controls{display:flex;flex-wrap:wrap;align-items:center;gap:8px 22px}.controls label{display:flex;align-items:center;justify-content:flex-start;gap:10px}.controls output{font-variant-numeric:tabular-nums;color:var(--blue)}
.controls label[for='worked-progress'],.controls label[for='worked-round']{flex:1 1 100%;justify-content:space-between}.controls input[type=range]{flex:1 1 100%;width:100%;min-height:26px;accent-color:var(--blue);margin:0}.controls select{font-size:14px;min-height:34px;padding:3px 9px}
.loss-table{border-collapse:collapse;width:100%;margin:28px 0;font-size:17px}.loss-table caption{text-align:left;font:14px/1.5 var(--sans);color:var(--muted);padding-bottom:12px}.loss-table th,.loss-table td{text-align:left;border-bottom:1px solid var(--light-rule);padding:12px 10px;font-weight:400}.loss-table thead th{font:13px/1.5 var(--sans);color:var(--muted)}.loss-table .math{font-size:22px;white-space:nowrap}
footer{display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap;border-top:1px solid var(--light-rule);padding:24px 4vw;font:14px/1.5 var(--sans)}.no-script{padding:24px;max-width:800px;margin:auto}
.footer-resources,.footer-links{width:100%}
.footer-resources p{margin:0 0 10px;color:var(--muted);font-size:13px}
.footer-resources nav{display:flex;flex-wrap:wrap;gap:8px 18px}
.footer-links{display:flex;justify-content:space-between;flex-wrap:wrap;gap:10px 20px}
@media(max-width:800px){
  html{scroll-padding-top:60px}.masthead{height:56px;padding:0 20px}.masthead>a span{display:none}.masthead nav{gap:18px}.reading-progress{top:55px}
  .title-page{min-height:calc(100svh - 56px);padding:32px 22px}.title-page h1{font-size:clamp(40px,10vw,60px)}.title-art{max-height:34svh;max-width:100%}.eyebrow{font-size:11px}
  .story-layout{display:block;padding:0 22px}.stage-shell{top:56px;height:66svh;min-height:470px;padding:8px 0;z-index:20;border-bottom:1px solid var(--rule)}.stage-top{font-size:12px;padding-bottom:5px}.visual-area{min-height:215px}
  .vector-readout{padding:4px 0;min-height:43px;gap:6px;font-size:12px}.vector-readout .value{font-size:15px;line-height:1.25}.vector-readout .readout-label{font-size:11px;line-height:1.25}
  .stage-shell[data-worked-scene='3'] .vector-readout>div:last-child,.stage-shell[data-worked-scene='5'] .vector-readout>div:last-child{display:none}
  .stage-caption{font-size:11px;line-height:1.3;min-height:30px;margin:5px 0}.stage-nav{padding-top:5px;font-size:12px}.stage-nav span{display:none}.stage-nav button{min-height:40px;padding:4px 12px;font-size:13px}
  .step{min-height:75svh;align-items:flex-start;padding:48px 0 65px;scroll-margin-top:calc(66svh + 66px)}.step>div{max-width:620px;margin:auto;width:100%}.step h2{font-size:32px;margin-bottom:20px}.step-number{margin-bottom:12px}.step p{font-size:17px;line-height:1.6}.step .quiet{font-size:15px}.step .equation{font-size:23px}
  .worked-controls{gap:3px 14px;padding:3px 0}.controls label{font-size:11px;gap:6px}.controls input[type=range]{min-height:24px}.controls select{min-height:28px;padding:2px 6px;font-size:12px}
  .loss-table{font-size:14px}.loss-table .math{font-size:18px}.loss-table th,.loss-table td{padding:10px 4px}
}
@media(max-width:540px){.masthead nav{gap:12px;font-size:12px}.masthead{padding:0 16px;gap:10px}}
@media(max-width:380px){
  .masthead>a{font-size:12px}.masthead nav{gap:9px;font-size:11px}.story-layout{padding:0 16px}.stage-top{font-size:11px}.step h2{font-size:29px}.vector-readout .value{font-size:14px}
  .stage-shell[data-worked-scene='2'] .vector-readout>div:nth-child(-n+2),.stage-shell[data-worked-scene='4'] .vector-readout>div:nth-child(-n+2){display:none}
  .loss-table th{max-width:100px}.loss-table .math{font-size:16px}
}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important}}
@media print{.masthead,.stage-shell,.reading-progress,.start-link,.skip-link{display:none}.title-page{min-height:0;padding:20px}.title-page h1{font-size:38px}.title-art{max-height:200px}.story-layout{display:block;max-width:760px}.step{min-height:0;padding:24px 0;break-inside:avoid}.step>div{max-width:none}.step h2{font-size:26px}footer{font-size:12px}}

/* The vector picture and exact norm slice belong to the main explanation. */
.prediction-diagram{width:100%;height:100%;min-width:0}
.loss-diagram{width:100%;height:100%;min-width:0}
.loss-controls{display:flex;flex-wrap:wrap;gap:6px 18px;align-items:center}
.loss-controls>label[for='loss-round']{flex:1 1 100%;justify-content:space-between}
.stage-shell[data-example='loss'] .visual-area{min-height:170px}
.stage-shell[data-example='loss']>.controls,.stage-shell[data-example='loss']>.vector-readout,.stage-shell[data-example='loss']>.stage-caption,.stage-shell[data-example='loss']>.stage-top,.stage-shell[data-example='loss']>.stage-nav{flex-shrink:0}
.table-scroll{overflow-x:auto}
@media(max-width:800px){
  .stage-shell[data-example='loss']{height:70svh;min-height:570px}
  .stage-shell[data-example='loss'] .visual-area{min-height:210px}
  .loss-controls{gap:3px 10px;padding:4px 0}
  .loss-controls>label{flex:1 1 calc(50% - 10px);min-width:0;font-size:11px;gap:4px}
  .loss-controls select{min-width:0;max-width:100%;font-size:11px;padding:2px 4px}
  .stage-shell[data-example='loss'] .vector-readout>div{flex:1 1 calc(50% - 6px)}
  .stage-shell[data-example='loss'] .vector-readout .value{font-size:14px}
  .step[data-loss-scene]{padding-top:20px}
}
.restricted-diagram{width:100%;height:100%;min-width:0}
.stage-shell[data-example='restricted']>.vector-readout,.stage-shell[data-example='restricted']>.restricted-controls,.stage-shell[data-example='restricted']>.stage-caption,.stage-shell[data-example='restricted']>.stage-top,.stage-shell[data-example='restricted']>.stage-nav{flex-shrink:0}
.restricted-controls{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:5px 18px;align-items:start}
.restricted-loss-label{grid-column:1;grid-row:1;padding-top:4px}
.restricted-loss-label select{min-width:0;max-width:100%}
.restricted-parameter{grid-column:2;grid-row:1;min-width:0}
.restricted-parameter>label,.restricted-prediction-controls>label{justify-content:space-between}
.restricted-weights{margin:0;color:var(--muted);font-size:11px;line-height:1.3}
.restricted-prediction-controls,.restricted-actions{grid-column:1/-1}
.restricted-actions{display:flex;gap:6px;align-items:center;flex-wrap:wrap}
.restricted-controls button{font:14px/1.4 var(--sans);min-height:36px;padding:4px 12px}
.restricted-rate{color:var(--muted)}
.stage-shell[data-example='restricted'] .visual-area{min-height:250px}
.stage-shell[data-example='restricted'] .vector-readout{gap:6px 16px;padding:7px 0;min-height:54px}
.stage-shell[data-example='restricted'] .stage-caption{font-size:13px;line-height:1.4;margin:8px 0}
.stage-shell[data-example='geometry']>.vector-readout,.stage-shell[data-example='geometry']>.geometry-controls,.stage-shell[data-example='geometry']>.stage-caption,.stage-shell[data-example='geometry']>.stage-top,.stage-shell[data-example='geometry']>.stage-nav{flex-shrink:0}
.geometry-controls{display:flex;flex-wrap:wrap;align-items:center;gap:6px 20px}
.geometry-controls>div{flex:1 1 100%}
.geometry-controls>div>label{justify-content:space-between}
.geometry-tree-actions{display:flex;flex-wrap:wrap;gap:6px;margin-left:auto}
.geometry-tree-actions button{font:13px/1.4 var(--sans);min-height:36px;padding:5px 9px}
#geometry-rate-label{order:-1}
@media(max-width:800px){
  .stage-shell[data-example='geometry']{height:60svh;min-height:500px}
  .stage-shell[data-example='restricted']{height:78svh;min-height:660px}
  .stage-shell[data-example='geometry'] .visual-area{min-height:220px}
  .stage-shell[data-example='geometry'] .vector-readout>div{flex:0 0 calc(50% - 3px)}
  .stage-shell[data-example='geometry'] .vector-readout{min-height:70px}
  .stage-shell[data-example='restricted'] .visual-area{min-height:240px}
  .stage-shell[data-example='restricted'] .vector-readout>div{flex:0 0 calc(50% - 3px)}
  .stage-shell[data-example='restricted'] .vector-readout{min-height:70px;gap:6px}
  .restricted-controls{gap:3px 10px;padding:3px 0}
  .restricted-loss-label{display:block!important;padding-top:0}
  .restricted-loss-label select{display:block;width:100%;margin-top:2px;font-size:11px;padding:2px 3px}
  .restricted-weights{font-size:10px}
  .restricted-actions{gap:4px 6px}
  .restricted-controls button{font-size:12px;min-height:30px}
  .restricted-rate{font-size:12px}
  .stage-shell[data-example='restricted'] .stage-caption{font-size:11px;line-height:1.3;margin:5px 0}
  .geometry-controls{gap:2px 12px;padding:3px 0}
  .step[data-geometry-scene]{padding-top:20px}
  .step[data-restricted-scene]{padding-top:20px}
}

/* The diagram leads; each chapter's explanation is a short card beneath it. */
.stage-top{grid-column:1/-1;grid-row:1;padding-bottom:7px}
.stage-top #stage-topic{font:17px/1.3 var(--sans);color:var(--ink)}
.stage-nav{grid-column:1/-1;grid-row:3;padding-top:8px}
.stage-tools{grid-column:2;grid-row:2;min-width:0;min-height:0;overflow-y:auto;overscroll-behavior:contain;padding:0 4px 0 16px;border-left:1px solid var(--light-rule);font:13px/1.45 var(--sans)}
.stage-tools>.controls{border-top:0;padding:0;display:flex;flex-direction:column;align-items:stretch;gap:10px}
.stage-tools .controls>label,.stage-tools .controls>div{flex:none;width:100%;min-width:0}
.stage-tools .controls label{font-size:13px;gap:8px}
.stage-tools .controls select{font-size:13px;min-height:34px;min-width:0;max-width:100%}
.stage-tools .controls input[type=range]{min-height:26px;margin:1px 0 0}
.stage-tools .restricted-loss-label{display:block!important;padding:0}
.stage-tools .restricted-loss-label select{display:block;width:100%;margin-top:4px}
.loss-equation{padding:8px 0 9px;border-bottom:1px solid var(--light-rule)}
.loss-equation-definition{display:flex;align-items:center;gap:5px;font-size:18px;line-height:1.35}
.loss-equation-total{font-size:14px;line-height:1.45;margin:7px 0 9px}
.loss-equation-shared{font-size:18px;line-height:1.4}
.loss-equation-domain{font:11px/1.4 var(--sans);color:var(--muted);margin:5px 0 0}
.stage-tools .restricted-parameter,.stage-tools .restricted-prediction-controls{width:100%}
.stage-tools .restricted-actions{gap:6px;display:flex;flex-wrap:wrap}
.stage-tools .restricted-actions button{font-size:13px;min-height:36px;padding:5px 9px}
.stage-tools .restricted-weights{font-size:11px;line-height:1.4;margin:3px 0 0}
.stage-tools .restricted-rate{font-size:12px}
.restricted-progression-controls,.restricted-sandbox-controls{display:flex;flex-direction:column;align-items:stretch;gap:12px}
.restricted-progression-controls>label{justify-content:space-between!important}
.stage-tools .restricted-progression-controls button{min-height:42px;color:var(--teal);border-color:var(--teal);background:#f0f8f6}
.stage-tools .restricted-progression-controls button:hover{background:#e3f3ef}
.restricted-sandbox-controls>.restricted-parameter,.restricted-sandbox-controls>.restricted-prediction-controls{min-width:0}
.restricted-sandbox-controls>.restricted-parameter>label,.restricted-sandbox-controls>.restricted-prediction-controls>label{justify-content:space-between}
.stage-tools .vector-readout{display:flex;flex-direction:column;flex-wrap:nowrap;gap:9px;min-height:0;border-top:0;padding:10px 0 4px}
.stage-tools .vector-readout>div{flex:none!important;width:100%}
.stage-tools .vector-readout .value{font-size:19px;line-height:1.3}
.stage-tools .vector-readout .readout-label{font-size:11px;line-height:1.3}
.stage-tools #numbers{border-top:1px solid var(--light-rule);padding:9px 0;margin-top:12px}
.stage-tools #numbers summary{font:12px/1.5 var(--sans);color:var(--muted);cursor:pointer;min-height:28px}
.stage-tools #numbers .vector-readout>div{display:block}
.stage-tools .stage-caption{font:13px/1.45 var(--sans);min-height:0;margin:14px 0 0}
.stage-shell[data-example] .visual-area{min-height:0}
.step .step-number{display:none}
.step>.step-content,.step>div{padding:0 8px}
.step .step-summary{font-size:19px;line-height:1.55;max-width:70ch}
.step .equation{font-size:24px;line-height:1.45;margin:14px 0}
.step details{border-top:1px solid var(--light-rule);margin-top:18px;padding-top:12px}
.step details summary{font:14px/1.5 var(--sans);color:var(--blue);cursor:pointer;min-height:32px}
.step details p{font-size:17px;line-height:1.55;margin:14px 0}
.step details .quiet{font-size:15px}
.step details .equation{font-size:22px}
@media(max-width:800px){
  .story-layout{padding:0 22px}
  .stage-shell,.stage-shell[data-example],.stage-shell[data-geometry-scene]{position:static;height:auto;min-height:0;display:grid;grid-template-columns:minmax(0,1fr);grid-template-rows:auto auto auto auto;row-gap:10px;padding:16px 0 14px;border-bottom:1px solid var(--light-rule)}
  .stage-top{grid-column:1;grid-row:1;font-size:12px;padding-bottom:7px}
  .stage-top #stage-topic{font-size:15px}
  .stage-top:has(.geometry-tree-actions:not([hidden])){flex-wrap:wrap}
  .stage-top .geometry-tree-actions{order:3;width:100%;margin-left:0}
  .stage-shell .visual-area,.stage-shell[data-example] .visual-area{grid-column:1;grid-row:2;height:clamp(280px,52svh,460px);min-height:0}
  .stage-tools{grid-column:1;grid-row:3;overflow:visible;min-height:0;padding:12px 0 0;border-left:0;border-top:1px solid var(--light-rule)}
  .stage-tools>.controls{gap:9px}
  .stage-tools .controls select{font-size:14px;min-height:38px}
  .stage-tools .controls label{font-size:13px}
  .stage-tools .controls input[type=range]{min-height:30px}
  .stage-tools .restricted-actions button{font-size:13px;min-height:40px;padding:6px 12px}
  .stage-tools .vector-readout{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px 14px}
  .stage-tools .vector-readout .value{font-size:17px}
  .stage-tools .stage-caption,.stage-shell[data-example] .stage-tools .stage-caption{font-size:13px;line-height:1.45;margin:12px 0 0}
  .stage-nav{grid-column:1;grid-row:4;padding-top:9px}
  .stage-nav button{min-height:42px;padding:6px 12px}
  .step,.step[data-geometry-scene],.step[data-restricted-scene],.step[data-loss-scene]{min-height:75svh;align-items:flex-start;padding:28px 0 45px;scroll-margin-top:74px}
  .step>div{max-width:840px;padding:0}
  .step h2{font-size:26px;margin-bottom:12px}
  .step .step-summary{font-size:18px;line-height:1.55}
  .step .equation{font-size:22px}
}
@media(max-width:380px){
  .masthead nav{min-width:0;flex:1;justify-content:flex-end;gap:8px}
  .masthead nav a{white-space:normal;text-align:center}
  .story-layout{padding:0 16px}
  .stage-tools .vector-readout{grid-template-columns:minmax(0,1fr)}
  .step h2{font-size:24px}
}
@media print{
  .stage-shell{display:none}
  .step{min-height:0;padding:24px 0}
  .step>div{padding:0}
  .step details{border:0;margin:0;padding:0}
  .step details summary{display:none}
}

/* The opening is a scroll-led figure, with each idea revealed in place. */
.visually-hidden{position:absolute!important;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.stage-shell[data-opening='true']{position:sticky;top:64px;height:calc(100svh - 80px);min-height:0;grid-template-columns:minmax(0,1fr);grid-template-rows:auto minmax(0,1fr) auto auto;column-gap:0;row-gap:8px;padding:10px 0 8px}
.stage-shell[data-opening='true']>.stage-tools{display:none}
.stage-shell[data-opening='true'] .visual-area{grid-column:1;grid-row:2;height:auto;min-height:0;align-self:stretch}
.stage-shell[data-opening='true']>.restricted-controls{grid-column:1;grid-row:3;display:flex;flex-direction:column;align-items:center;gap:8px;border:0;padding:0 0 2px;font:13px/1.4 var(--sans)}
.restricted-loss-options{display:flex;justify-content:center;gap:6px;flex-wrap:wrap}
.stage-shell[data-opening='true'] .restricted-actions{justify-content:center;gap:6px}
.stage-shell[data-opening='true'] .restricted-controls button{min-height:36px;padding:5px 11px;font:13px/1.4 var(--sans)}
.restricted-loss-options button[aria-pressed='true']{color:var(--teal);border-color:var(--teal);background:#eef7f5}
.stage-shell[data-opening='true'] .stage-nav{grid-column:1;grid-row:4;padding-top:8px}
.opening-nav-tools{display:flex;align-items:center;justify-content:center;gap:12px}
#opening-replay{font:12px/1.3 var(--sans);min-width:0;min-height:32px;padding:4px 8px;border-color:transparent;color:var(--muted);background:transparent}
#opening-replay:hover{color:var(--blue);background:#f1f5f7}
.opening-annotation{position:absolute;z-index:3;top:12px;left:14px;max-width:32ch;margin:0;padding:6px 10px;font:15px/1.45 var(--sans);color:var(--ink);background:rgba(255,255,255,.92);pointer-events:none;transition:opacity .25s,transform .25s}
.opening-annotation:empty{display:none}
.opening-annotation p{margin:0}
.opening-annotation .opening-round{display:block;margin-bottom:3px;font-size:12px;color:var(--muted)}
.opening-annotation>.math{display:block;margin-top:5px;font-size:18px;line-height:1.35}
.opening-annotation[data-loss-equation='true']{top:4px;left:12px;right:12px;width:fit-content;max-width:calc(100% - 24px);padding:3px 6px;font-size:13px;line-height:1.4}
.opening-annotation[data-loss-equation='true']>.math{margin-top:4px;font-size:18px;line-height:1.4}
.opening-annotation .loss-equation-signed{display:flex;flex-wrap:wrap;align-items:center;justify-content:center;gap:6px 18px}
.opening-annotation .loss-equation-residual,.opening-annotation .loss-equation-definition{font-size:18px;line-height:1.4;white-space:nowrap}
.loss-equation-signed math{font-family:'Course Math','Cambria Math',math;font-size:inherit}
.loss-equation-signed mtd{padding:0 .35em}
.loss-equation-definition:has([data-loss-case='quadratic']){font-size:17px}
.step[data-restricted-scene]{min-height:68svh;padding:28px 0 44px}
.step[data-restricted-scene]>div{max-width:700px}
.step[data-restricted-scene] h2{font-size:clamp(24px,2vw,28px)}
.step[data-restricted-scene] .step-summary{font-size:18px;max-width:58ch;margin-bottom:0}
.worked-transition-diagram{width:100%;height:100%;display:grid;place-items:center;text-align:center;padding:24px}
.worked-transition-diagram>div{max-width:650px;animation:transition-reveal .5s ease-out both}
.worked-transition-diagram .eyebrow{color:var(--teal);margin-bottom:22px}
.worked-transition-diagram h2{font-size:clamp(38px,6vw,64px);margin:0 0 24px}
.worked-transition-diagram p:not(.eyebrow){font-size:clamp(18px,2.2vw,25px);line-height:1.5;max-width:32ch;margin:0 auto}
.worked-transition-diagram p.transition-process{font:15px/1.7 var(--sans);color:var(--blue);padding-top:36px}
.transition-process span{display:inline-block;padding:0 .4em;color:var(--teal)}
.step[data-transition-scene]{min-height:68svh;padding:28px 0 44px}
@keyframes transition-reveal{from{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}
@media(max-width:800px){
  .stage-shell[data-opening='true']{position:sticky;top:56px;height:calc(100svh - 56px);min-height:0;grid-template-rows:auto minmax(0,1fr) auto auto;padding:9px 0 8px;row-gap:8px}
  .stage-shell[data-opening='true'] .visual-area{height:auto;min-height:0;grid-column:1;grid-row:2}
  .stage-shell[data-opening='true'] .stage-top #stage-topic{font-size:14px}
  .stage-shell[data-opening='true'] .stage-nav{grid-row:4}
  .stage-shell[data-opening='true'] .restricted-controls button{min-height:34px;padding:5px 9px;font-size:12px}
  .stage-shell[data-opening='true']>.restricted-controls{gap:6px}
  .restricted-loss-options,.stage-shell[data-opening='true'] .restricted-actions{gap:5px}
  .opening-annotation{top:5px;left:0;right:0;width:fit-content;max-width:calc(100% - 12px);margin:0 auto;padding:6px 8px;font-size:13px;line-height:1.4;text-align:center}
  .step[data-restricted-scene]{min-height:72svh;padding:24px 0 40px}
  .step[data-restricted-scene] h2{font-size:24px}
  .step[data-restricted-scene] .step-summary{font-size:17px}
  .stage-shell[data-opening='false']{position:sticky;top:56px;height:calc(100svh - 56px);min-height:0;grid-template-columns:minmax(0,1fr);grid-template-rows:auto minmax(200px,40svh) minmax(0,1fr) auto;padding:9px 0 8px;row-gap:8px}
  .stage-shell[data-opening='false'] .visual-area{grid-column:1;grid-row:2;height:auto;min-height:0;align-self:stretch}
  .stage-shell[data-opening='false']>.stage-tools{grid-column:1;grid-row:3;min-height:0;overflow-y:auto;overscroll-behavior:contain;padding:9px 2px 2px;border-top:1px solid var(--light-rule)}
  .stage-shell[data-opening='false'] .stage-nav{grid-column:1;grid-row:4;min-height:0;padding-top:8px}
  .stage-shell[data-opening='false'] .stage-top #stage-topic{font-size:14px}
}
@media(max-width:800px) and (max-height:520px){
  .stage-shell[data-opening='false']{grid-template-rows:auto minmax(110px,34svh) minmax(0,1fr) auto;row-gap:5px;padding:6px 0}
  .stage-shell[data-opening='false'] .stage-nav button{min-height:34px;padding:4px 10px}
}
@media(max-width:400px){
  .opening-annotation .loss-equation-residual,.opening-annotation .loss-equation-definition{font-size:16px}
}
@media print{
  .stage-shell[data-opening='true']{display:none}
  .step[data-restricted-scene]{min-height:0;padding:24px 0}
}