:root{--paper:#f4f1e8;--canvas:#e9e5d9;--ink:#343831;--secondary:#686d61;--rule:#c9c9ba;--accent:#ac4d23}*{box-sizing:border-box}html,body{margin:0;min-height:100%;background:var(--paper);color:var(--ink);font-family:Arial,'PingFang SC','Microsoft YaHei','Noto Sans CJK SC',sans-serif}button,a{-webkit-tap-highlight-color:transparent;touch-action:manipulation}button{font:inherit;color:inherit;cursor:pointer;border:1px solid var(--rule);background:transparent}a{color:inherit;text-decoration:none}button:focus-visible,a:focus-visible{outline:2px solid var(--accent);outline-offset:3px}button:disabled{opacity:.35;cursor:default}button[hidden],[hidden]{display:none!important}button:hover:not(:disabled),a.case-card:hover{background:#e8e5da}button:disabled:hover{background:transparent}.text-button{border:0;border-bottom:1px solid var(--rule);padding:8px 0;font-size:12px}.cases-page{max-width:1280px;margin:0 auto;padding:58px 48px 28px}.cases-head{display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--ink);padding-bottom:24px}.sheet-label{font:10px/1.5 monospace;letter-spacing:1.2px;margin:0 0 12px;color:var(--secondary)}h1{font-weight:500}.cases-head h1{font-size:27px;letter-spacing:2px;margin:0}.model-grid{display:grid;grid-template-columns:repeat(3,1fr);margin-top:32px;border:1px solid var(--rule)}.case-card{display:flex;flex-direction:column;position:relative;min-width:0;padding:18px 21px 22px;transition:background .15s}.case-card+.case-card{border-left:1px solid var(--rule)}.case-topline{font:10px monospace;color:var(--secondary);display:flex;justify-content:space-between}.case-card img{display:block;width:100%;height:265px;object-fit:contain;margin:12px 0 7px;mix-blend-mode:multiply}.case-card .thumbnail-placeholder{height:265px;display:grid;place-items:center;font-size:12px;color:var(--secondary)}.case-card 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var(--accent)}.stage-bottom{position:absolute;bottom:16px;left:23px;right:22px;display:flex;justify-content:space-between;align-items:center;gap:16px;pointer-events:none}.stage-bottom>div{display:flex;align-items:center;gap:8px;pointer-events:auto}.orbit-hint,#overview-note{font-size:10px;color:#818778;letter-spacing:.2px}.tool-button{font-size:11px;padding:9px 13px;min-height:37px;background:#f4f1e8ec;border-color:#afb3a4;border-radius:0}.tool-button.active{border-color:#5c6652;background:#e2e3d6}.instruction-panel{position:relative;border-top:1px solid #bfc3b4;background:var(--paper);display:grid;grid-template-columns:minmax(230px,1.15fr) minmax(250px,1.2fr) 222px;gap:27px;padding:19px 24px 18px;min-height:152px;align-items:center}.instruction-summary{align-self:start}.panel-eyebrow{font:10px monospace;letter-spacing:1.2px;color:#7c8273;display:flex;gap:7px;align-items:center}.step-number{color:var(--accent)}.panel-title{font-weight:500;font-size:19px;margin:8px 0 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h3{font-size:13px;font-weight:500;color:#4d5d3f;margin:23px 0 8px}.guide-content p{margin:0}.guide-content .safety{padding:15px 0;border-block:1px solid #c8cdbd;margin:22px 0 15px;font-size:11px;color:#767b62}.guide-content .credits{font-size:10px;color:#8d947e}.guide-content a{text-decoration:underline}#toast{position:fixed;bottom:60px;left:50%;transform:translate(-50%,12px);background:#3e4837;color:#f5f4e8;padding:12px 18px;font-size:12px;opacity:0;pointer-events:none;transition:.2s;z-index:20;text-align:center;max-width:90vw}#toast.visible{opacity:1;transform:translate(-50%,0)}
@media(min-width:1550px){.instruction-panel{grid-template-columns:1.2fr 1.2fr 230px;gap:45px;padding-inline:35px}.drawing-label,.view-switch{left:35px}.stage-tools{right:35px}.case-card img{height:310px}}
@media(max-width:1050px){.cases-page{padding:40px 28px 25px}.case-card{padding:16px}.case-card img{height:220px}.case-card h2{font-size:18px}.instruction-panel{grid-template-columns:minmax(180px,1fr) minmax(180px,1fr) 192px;gap:18px;padding:17px 20px}.panel-title{font-size:17px}.panel-desc{font-size:11px}.part-item{min-width:107px;padding-inline:5px;gap:4px}.part-item svg{width:40px}.panel-tip{font-size:9px}.model-facts{gap:18px}.model-facts strong{font-size:22px}}
@media(max-width:700px){.cases-page{padding:29px 20px 22px}.cases-head{padding-bottom:20px}.cases-head h1{font-size:24px}.sheet-label{font-size:9px;margin-bottom:10px}.text-button{font-size:11px}.model-grid{grid-template-columns:1fr;margin-top:23px}.case-card{padding:16px 18px 18px}.case-card+.case-card{border-left:0;border-top:1px solid var(--rule)}.case-card img{height:200px;margin:0}.case-card h2{font-size:20px;margin:0 0 6px}.case-topline{font-size:9px}.case-meta{font-size:11px}.case-footer{margin-top:14px;padding-top:12px;font-size:11px}.cases-foot{display:block;margin-top:20px}.cases-foot p:last-child{text-align:left;margin-top:13px;font-size:9px}.build-page{min-height:600px;grid-template-rows:46px minmax(0,1fr) auto 42px}.build-header{padding:0 12px;gap:12px}.back-link{font-size:11px;gap:5px}.build-header h1{font-size:12px;padding-left:12px}.header-reference{display:none}.header-actions{gap:12px}.header-actions button{font-size:10px;padding:12px 0}.header-actions span{font-size:9px;margin-left:2px}.header-actions button:last-child{display:none}.view-switch{left:12px;top:12px}.view-switch button{padding:8px 12px;font-size:10px;min-height:33px}.stage-tools{right:12px;top:12px}.stage-tools button{width:32px;height:33px;font-size:19px}.drawing-label{left:13px;top:65px;gap:6px}.drawing-label>span:first-child{font-size:8px;letter-spacing:.7px}.drawing-label>span:nth-child(2){font-size:10px}.drawing-label small{font-size:8px}.stage-legend{right:13px;top:65px;font-size:8px;gap:8px}.stage-legend i{width:9px;height:8px}.stage-bottom{left:12px;right:12px;bottom:12px;align-items:flex-end;gap:7px}.orbit-hint{font-size:8px;line-height:1.6;max-width:90px}.stage-bottom>div{gap:6px}.tool-button{min-height:34px;padding:8px 10px;font-size:9px}#overview-note{font-size:9px}.instruction-panel{grid-template-columns:minmax(0,1fr) 132px;gap:12px 16px;padding:13px 14px;min-height:0}.instruction-summary{grid-column:1 / -1;display:grid;grid-template-columns:auto 1fr;column-gap:11px;align-items:baseline}.panel-eyebrow{font-size:9px;letter-spacing:.5px}.panel-title{font-size:15px;line-height:1.5;margin:0}.panel-desc{grid-column:1 / -1;font-size:11px;line-height:1.65;margin-top:6px}.panel-parts{min-width:0}.parts-heading{font-size:9px;margin:0 0 5px}.parts-list{gap:5px}.part-item{min-width:88px;padding:6px 6px 4px;gap:3px;min-height:57px}.part-item svg{width:34px;height:32px}.part-name{font-size:8px}.part-name small{font-size:7px}.part-count{font-size:9px;top:3px;right:4px}.panel-tip{font-size:9px;line-height:1.6;margin-top:4px;max-height:30px;overflow:auto}.panel-actions{align-self:start;padding-top:16px}.main-action{font-size:10px;min-height:41px;padding:10px 9px;gap:4px}.back-button{width:31px;min-height:41px;font-size:16px}.panel-nav{gap:5px}.panel-footnote{font-size:8px;margin:7px 0 0;line-height:1.5}.model-facts{gap:20px;margin-bottom:0;padding-top:1px}.model-facts strong{font-size:20px}.model-facts small{font-size:8px;margin-top:4px}.overview-support{display:none}.step-timeline{padding:0 12px;gap:5px}.timeline-label{font-size:9px;margin-right:3px}.timeline-step{width:26px;min-width:26px;height:26px;font-size:9px}.timeline-progress{display:none}dialog{padding:20px 17px;max-height:88vh}.dialog-head h2{font-size:18px}.dialog-head{padding-bottom:15px}.dialog-desc{font-size:11px}.inventory-list .part-item{padding:10px 5px;gap:5px}.inventory-list .part-item svg{width:42px;height:37px}.inventory-list .part-name{font-size:10px}.inventory-list .part-name small{font-size:9px}.inventory-list .part-count{font-size:11px;right:6px;top:5px}.inventory-footer{display:block}.inventory-footer p{font-size:10px;margin-bottom:13px}.inventory-footer button{width:100%}.guide-content{font-size:11px}.guide-content h3{font-size:12px}}
@media(max-width:380px){.build-header h1{font-size:11px}.header-actions span{display:none}.instruction-panel{grid-template-columns:minmax(0,1fr) 115px;gap:10px}.panel-title{font-size:14px}.panel-desc{font-size:10px}.main-action{font-size:9px}.stage-tools button{width:29px}.view-switch button{padding-inline:10px}.tool-button{font-size:8px;padding-inline:8px}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{transition:none!important;animation:none!important}}
/* Picture-first controls: text lives in the parent help sheet. */
.sr-only{position:absolute!important;width:1px;height:1px;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0;padding:0}.case-card{padding:12px 18px 20px}.case-card img{height:300px;margin:0}.case-caption{display:flex;align-items:center;justify-content:space-between;gap:12px}.case-caption h2{font-size:15px;margin:0;color:#737c67}.case-start{width:51px;height:51px;border:1px solid #7f8974;display:grid;place-items:center;border-radius:50%;background:#e5e7da;color:#56654a}.case-start svg{width:28px;height:28px}.cases-head h1{font-size:20px;color:#5c6751}.cases-head{padding-bottom:18px}.cases-head button{width:48px;height:48px;display:grid;place-items:center;border:1px solid #bac1ad;border-radius:50%}.cases-head button svg{width:26px;height:26px}.case-card:focus-visible,.case-card:hover{outline:2px solid #71825d;outline-offset:-2px}.cases-foot{font-size:10px}.build-page{grid-template-rows:54px minmax(0,1fr) auto 42px}.build-header{gap:16px;padding-inline:18px}.back-link{width:45px;height:45px;justify-content:center;padding:8px}.back-link svg{width:25px;height:25px}.build-header h1{font-size:12px;color:#79816f;border-left:0;padding-left:0}.header-actions{gap:9px;align-items:center}.header-actions button{width:44px;height:44px;padding:9px;display:grid;place-items:center}.header-actions button svg{width:26px;height:26px}.view-switch{left:17px;top:15px;border:1px solid #9da88e;border-radius:8px;overflow:hidden}.view-switch button{width:52px;height:48px;padding:10px}.view-switch button svg{width:28px;height:28px}.view-switch button.active{background:#d8dfcb}.stage-tools{right:17px;top:15px;border-radius:8px;overflow:hidden}.stage-tools button{width:43px;height:47px;font-size:24px}.drawing-label{left:20px;top:79px;gap:0}.drawing-label>span:first-child{font:15px monospace;color:#76836a;letter-spacing:1px}.drawing-label>span:nth-child(2){display:none}.stage-bottom{bottom:18px;left:19px;right:18px;gap:12px}.orbit-hint{display:inline-block;color:#869277}.orbit-hint svg{width:41px;height:41px}.stage-bottom>div{gap:10px}.tool-button{border:1px solid #94a17f;min-width:53px;height:53px;padding:11px;border-radius:9px;background:#f4f1e8ef;display:grid;place-items:center}.tool-button svg{width:29px;height:29px}#replay-button{background:#e0e7d3;border-color:#83966a;width:58px;height:58px}#replay-button[aria-pressed="false"]{background:#eef0e5}.instruction-panel{grid-template-columns:45px minmax(0,1fr) 160px;gap:20px;padding:14px 24px;min-height:110px;align-items:center}.tray-mark,.visual-summary{color:#8f9c7e;display:grid;place-items:center}.tray-mark svg,.visual-summary svg{width:31px;height:31px}.picture-tray{display:flex;gap:14px;align-items:center;overflow-x:auto;scrollbar-width:thin;min-width:0;padding-bottom:4px}.picture-part{flex:0 0 93px;min-height:78px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:3px;background:#eceee2;border:1px solid #c5cdb8;border-radius:6px;padding:3px 6px 9px}.picture-part>img{width:80px;height:54px;object-fit:contain;mix-blend-mode:multiply}.picture-part>svg{width:72px;height:54px}.quantity-dots{display:flex;justify-content:center;flex-wrap:wrap;gap:5px;max-width:60px;min-height:7px}.quantity-dots i{width:6px;height:6px;border-radius:50%;background:#687956}.child-nav{display:flex;gap:14px;justify-content:flex-end;align-items:center}.child-button{width:60px;height:60px;display:grid;place-items:center;border:1.5px solid #9cae87;border-radius:50%;background:#edf0e3;color:#687b52;flex:none}.child-button svg{width:31px;height:31px;stroke-width:2.5}.child-button.next-button,.child-button.start-button{background:#66834e;border-color:#55763c;color:#fffdf3}.child-button:hover:not(:disabled){background:#d9e4c8}.child-button.next-button:hover,.child-button.start-button:hover{background:#526f3d}.child-button.start-button{width:68px;height:68px}.ready-pictures{display:flex;gap:11px;align-items:center;overflow:hidden}.ready-pictures>span{width:75px;flex:none}.ready-pictures img{width:75px;height:60px;object-fit:contain;mix-blend-mode:multiply}.ready-pictures svg{width:65px;height:55px}.success-symbol{width:55px;height:55px;border:2px solid #7c985f;border-radius:50%;display:grid;place-items:center;color:#6a8d4b}.success-symbol svg{width:33px;height:33px;stroke-width:2.5}.success-pictures img{height:90px;max-width:190px;object-fit:contain;mix-blend-mode:multiply}.step-timeline{justify-content:center;gap:8px}.timeline-step{width:28px;min-width:28px;height:28px;border:0;border-radius:50%;font-size:10px;color:#bac4a9}.timeline-step.active{background:none;border:2px solid #718d53;color:#718d53}.timeline-step.complete{background:#dfe7d3;color:#748d5b;font-size:13px}.picture-tray:focus-visible{outline:2px solid #8da671}#current-step-help{padding-bottom:8px}#current-step-help hr{border:0;border-top:1px solid #bbc6ad;margin-top:18px}
@media(max-width:1050px){.instruction-panel{grid-template-columns:32px minmax(0,1fr) 142px;gap:13px;padding:12px 18px}.picture-tray{gap:9px}.picture-part{flex-basis:84px}.picture-part>img{width:73px}.child-button{width:57px;height:57px}.child-nav{gap:11px}.case-card img{height:235px}}
@media(max-width:700px){.cases-head h1{font-size:18px}.cases-head button{width:44px;height:44px}.case-card img{height:215px}.case-card{padding:9px 17px 16px}.case-caption h2{font-size:14px}.case-start{width:49px;height:49px}.build-page{grid-template-rows:51px minmax(0,1fr) auto 37px;min-height:610px}.build-header{padding:0 9px;gap:8px}.build-header h1{font-size:10px}.back-link{width:41px;height:43px}.back-link svg{width:24px;height:24px}.header-actions{gap:5px}.header-actions button,.header-actions button:last-child{display:grid;width:39px;height:43px;padding:8px}.header-actions button svg{width:25px;height:25px}.view-switch{left:11px;top:12px}.view-switch button{width:46px;height:43px;padding:9px}.view-switch button svg{width:26px;height:26px}.stage-tools{right:11px;top:12px}.stage-tools button{width:35px;height:43px;font-size:23px}.drawing-label{left:13px;top:69px}.drawing-label>span:first-child{font-size:12px}.stage-bottom{left:13px;right:12px;bottom:14px}.orbit-hint svg{width:33px;height:33px}.tool-button{min-width:48px;height:48px;padding:10px}.tool-button svg{width:27px;height:27px}#replay-button{width:54px;height:54px}.instruction-panel{grid-template-columns:minmax(0,1fr) 110px;gap:10px;padding:10px 12px;min-height:95px}.tray-mark,.visual-summary{display:none}.picture-tray{gap:7px}.picture-part{flex-basis:72px;min-height:72px;padding:2px 3px 7px;border-radius:5px}.picture-part>img{width:64px;height:48px}.picture-part>svg{width:58px;height:48px}.quantity-dots{gap:4px;max-width:52px}.quantity-dots i{width:5px;height:5px}.child-nav{gap:8px}.child-button{width:50px;height:50px}.child-button svg{width:27px;height:27px}.child-button.start-button{width:59px;height:59px}.ready-pictures{gap:4px}.ready-pictures>span,.ready-pictures img{width:57px}.ready-pictures img{height:49px}.success-symbol{display:none}.success-pictures img{height:73px}.step-timeline{gap:5px;padding:0 9px}.timeline-step{min-width:23px;width:23px;height:23px;font-size:8px}.timeline-step.complete{font-size:11px}}
/* Quiet control family; secondary/adult tools no longer compete with the model. */
.cases-head button{width:auto;height:44px;min-width:44px;padding:0 2px;border:0;border-radius:0;background:transparent;font-size:11px;color:#7a806f;box-shadow:none}.cases-head button:hover{background:transparent;color:#3e4d32}.build-page{grid-template-rows:54px minmax(0,1fr) auto}.header-actions button#details-button{border:0;width:44px;height:44px;font-size:11px;border-radius:0;color:#7a806f}.header-actions #inventory-button,.tray-mark,.orbit-hint{display:none!important}.instruction-panel{grid-template-columns:minmax(0,1fr) 150px;gap:20px;padding:10px 20px;min-height:104px}.picture-tray{gap:3px;flex-wrap:wrap;max-height:160px;overflow:auto;align-content:center;padding:0}.picture-piece{width:75px;height:67px;display:flex;align-items:center;justify-content:center;flex:none;background:none;border:0;position:relative}.picture-piece>img{width:75px;height:66px;object-fit:contain;mix-blend-mode:multiply}.picture-piece>svg{width:65px;height:54px}.visual-summary{display:none}.child-nav{gap:8px}.child-button,.child-button.start-button{width:58px;height:58px;border-radius:6px;background:transparent;border:1px solid #afb5a3;color:#58664b;box-shadow:none}.child-button.next-button,.child-button.start-button{background:#e3e7d9;border-color:#8c9d78;color:#4f6840}.child-button svg{stroke-width:1.7;width:28px;height:28px}.child-button:hover:not(:disabled){background:#e7ebdf}.child-button.next-button:hover,.child-button.start-button:hover{background:#dce3d0}.tool-button,#replay-button{border-radius:5px;width:52px;height:52px;background:#f4f1e8e8;border:1px solid #a3ad94;box-shadow:none}.tool-button svg{stroke-width:1.7;width:27px;height:27px}#replay-button[aria-pressed="true"]{background:#e8ecde}#explode-button{display:none!important}.case-start{border:0;border-radius:0;background:none;color:#5c704a;width:44px;height:44px}.case-start svg{width:25px;height:25px}.case-card img{height:235px}.model-grid{grid-template-columns:repeat(3,minmax(0,1fr));border:0;gap:0}.case-card{border:1px solid var(--rule);margin-right:-1px;margin-bottom:-1px}.case-card+.case-card{border-left:1px solid var(--rule)}.adult-tools{display:flex;gap:9px;padding:15px 0;flex-wrap:wrap}.adult-tools button{font-size:11px;min-height:40px;padding:9px 12px;border:1px solid #afb99e;background:none}.guide-content .step-timeline{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));padding:5px 0 15px;gap:5px;max-height:260px;overflow:auto;border-bottom:1px solid #c2cbb5;border-top:0}.guide-content .timeline-step{font:10px/1.6 Arial,sans-serif;text-align:left;border:1px solid #c6cdbb;border-radius:0;width:auto;height:auto;min-height:36px;padding:8px;color:#6c795d;background:none}.guide-content .timeline-step.active{background:#e0e7d5;border:1px solid #8d9e77;color:#52663e}.guide-content .timeline-step.complete{background:#eef0e8;color:#78856c}.success-symbol{display:none}
@media(max-width:700px){.model-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.case-card{padding:8px 10px 12px}.case-card img{height:155px}.case-caption h2{font-size:12px;line-height:1.5}.case-start{width:32px;height:36px;flex:none}.case-start svg{width:20px;height:20px}.build-page{grid-template-rows:51px minmax(0,1fr) auto;min-height:610px}.instruction-panel{grid-template-columns:minmax(0,1fr) 104px;padding:8px 9px;gap:9px;min-height:85px}.picture-tray{gap:0;max-height:126px}.picture-piece{width:57px;height:56px}.picture-piece>img{width:57px;height:55px}.picture-piece>svg{width:53px;height:49px}.child-nav{gap:5px}.child-button,.child-button.start-button{width:48px;height:48px;border-radius:5px}.child-button svg{width:25px;height:25px}.tool-button,#replay-button{width:48px;height:48px}.header-actions button#details-button{font-size:10px}.success-pictures img{height:75px}.cases-head button{height:44px;font-size:10px}.guide-content .timeline-step{font-size:9px}}
.view-switch{background:#f4f1e8e8;border-color:#abb39c}.view-switch button{width:69px;height:51px;padding:4px 7px}.view-switch button>img{width:55px;height:43px;object-fit:contain;mix-blend-mode:multiply}.step-mode-picture{display:flex;align-items:center;justify-content:center}.step-mode-picture img{width:42px;height:39px;object-fit:contain;mix-blend-mode:multiply}.step-mode-picture svg{width:38px;height:35px}.step-mode-picture>span{font-size:20px;color:#758363;margin-left:1px}.view-switch button.active{background:#e2e7d7;box-shadow:inset 0 -2px 0 #8b9a73}
@media(max-width:700px){.view-switch button{width:59px;height:46px;padding:3px 5px}.view-switch button>img{width:48px;height:40px}.step-mode-picture img{width:34px;height:35px}.step-mode-picture>span{font-size:18px}.picture-tray{max-height:180px}}
.case-copy small{display:block;font-size:9px;color:#969d89;margin-top:6px;letter-spacing:.2px}.case-caption{align-items:center}

/* Framing: every control occupies layout space, never covers the canvas. */
.build-page{height:100dvh;min-height:0;grid-template-rows:auto minmax(0,1fr) auto}
.build-header{min-height:49px;padding-top:env(safe-area-inset-top)}
.drawing-area{display:grid;grid-template-rows:auto minmax(0,1fr);overflow:hidden}
.drawing-toolbar{display:flex;align-items:center;gap:14px;padding:7px 16px;background:var(--paper);border-bottom:1px solid var(--rule);min-width:0}
.drawing-toolbar .view-switch,.drawing-toolbar .stage-tools,.drawing-toolbar .drawing-label{position:static;flex:none}
.drawing-toolbar .view-switch{margin:0}.drawing-toolbar .drawing-label{margin-right:auto;gap:0}
.drawing-toolbar .drawing-label>span:empty{display:none}.drawing-toolbar .drawing-label>span:first-child{font-size:11px;letter-spacing:.5px}
.drawing-toolbar .stage-tools{margin-left:auto}.drawing-toolbar .view-switch button{height:46px}
.stage{position:relative;inset:auto;min-width:0;min-height:0;overflow:hidden;grid-row:2}
.stage-legend{display:none!important}
.instruction-dock{display:flex;align-items:center;min-width:0;border-top:1px solid var(--rule);background:var(--paper);padding:0 0 env(safe-area-inset-bottom)}
.playback-control{padding:9px 0 9px 15px;flex:none}.playback-control:has(#replay-button[hidden]){display:none}
.instruction-panel{flex:1;min-width:0;border-top:0;min-height:86px;grid-template-columns:minmax(0,1fr) auto;padding:8px 16px;gap:14px}
.picture-tray{max-height:134px;overflow:auto}.instruction-panel .child-nav{flex:none}
@media(max-width:700px){.build-page{min-height:0;grid-template-rows:auto minmax(0,1fr) auto}.build-header{min-height:45px}.drawing-toolbar{padding:5px 8px;gap:8px}.drawing-toolbar .view-switch button{height:40px;width:51px;padding:2px}.drawing-toolbar .view-switch button>img{width:43px;height:35px}.drawing-toolbar .stage-tools button{width:35px;height:39px}.drawing-toolbar .drawing-label>span:first-child{font-size:10px}.instruction-panel{padding:7px 8px;gap:7px;min-height:76px}.playback-control{padding:7px 0 7px 8px}.picture-tray{max-height:112px}.picture-piece{width:53px;height:53px}.picture-piece>img{width:53px;height:51px}.child-button,.child-button.start-button{width:44px;height:46px}.child-nav{gap:4px}.tool-button,#replay-button{width:44px;height:46px}}
@media(max-height:500px){.build-header{min-height:38px}.drawing-toolbar{padding-top:3px;padding-bottom:3px}.drawing-toolbar .view-switch button{height:36px}.drawing-toolbar .view-switch button>img{height:31px}.instruction-panel{min-height:64px;padding-top:4px;padding-bottom:4px}.picture-tray{flex-wrap:nowrap;overflow-x:auto;max-height:55px}.picture-piece{flex:0 0 53px;height:51px}.picture-piece>img{height:49px}.playback-control{padding-top:4px;padding-bottom:4px}.child-button,.child-button.start-button,.tool-button,#replay-button{height:44px}}

/* Neutral white sheet, requested instead of yellow-green paper. */
:root{--paper:#fafafa;--canvas:#f6f6f6;--ink:#343b40;--secondary:#737b82;--rule:#d4d8db}
.stage{background:radial-gradient(ellipse at 50% 45%,#fff 0%,#f3f3f3 100%)}
button:hover:not(:disabled),a.case-card:hover{background:#f0f2f3}
.drawing-toolbar .view-switch,.drawing-toolbar .stage-tools{background:#fafafa;border-color:#c1c8cd}
.view-switch button+button,.stage-tools button+button{border-color:#c1c8cd}
.view-switch button.active{background:#e9edf0;box-shadow:inset 0 -2px 0 #8998a4;color:#35444e}
.drawing-label>span:first-child,.drawing-label>span:nth-child(2),.stage-tools button,.case-start,.case-copy small{color:#7a858e}
.child-button,.child-button.start-button{border-color:#bdc6cd;color:#576773;background:transparent}
.child-button.next-button,.child-button.start-button{background:#e9eef2;border-color:#a6b5c0;color:#496272}
.child-button:hover:not(:disabled),.child-button.next-button:hover,.child-button.start-button:hover{background:#e0e7ec}
.tool-button,#replay-button{background:#fafafa;border-color:#b7c2ca;color:#4c616f}#replay-button[aria-pressed="true"]{background:#edf1f3}
.header-actions button#details-button,.cases-head button{color:#7c858c}.case-card{border-color:var(--rule)}
dialog{border-color:#c1c8ce;box-shadow:0 15px 80px #232d3526}dialog::backdrop{background:#23292f6b}.guide-content p,.guide-content h3,.dialog-desc,.dialog-head .eyebrow{color:#68727a}
.category-nav{display:flex;gap:10px;overflow-x:auto;padding:18px 0 8px;margin-top:3px;scrollbar-width:thin}
.category-choice{display:flex;flex:0 0 130px;flex-direction:column;align-items:center;gap:6px;border:1px solid transparent;border-radius:3px;padding:5px 9px 10px;color:#8b949b;font-size:11px;line-height:1.3}
.category-choice.active{border-color:#adb9c2;color:#405565;background:#eef2f5}.category-choice:hover{background:#f1f4f6}
.category-picture{display:flex;width:109px;height:68px;align-items:center;justify-content:center}.category-picture img{width:100%;height:100%;object-fit:contain;mix-blend-mode:multiply}.category-mosaic{display:grid;grid-template-columns:1fr 1fr;grid-template-rows:1fr 1fr;gap:0}.category-mosaic img{min-height:0;min-width:0}
.model-grid{margin-top:16px}
@media(max-width:700px){.category-nav{gap:5px;padding-top:12px}.category-choice{flex-basis:92px;font-size:10px;padding:4px 6px 8px}.category-picture{width:78px;height:52px}.model-grid{margin-top:10px}}
/* Difficulty and bounded case pages: picture-first, no quality badges. */
.difficulty-nav{display:flex;align-items:center;gap:7px;margin:14px 0 8px}.difficulty-choice{min-width:72px;min-height:48px;display:flex;align-items:center;justify-content:center;border:1px solid transparent;border-radius:3px;color:#8a949b}.difficulty-choice.active{border-color:#9cabb6;background:#edf1f4;color:#435d70}.difficulty-choice svg{width:23px;height:23px}.stars{letter-spacing:3px;font-size:17px;white-space:nowrap}.case-copy small{display:flex;align-items:center;gap:10px;flex-wrap:wrap}.case-copy small .stars{font-size:13px;color:#677d8b}.catalog-pager{display:flex;justify-content:center;align-items:center;gap:26px;margin:26px 0 8px}.page-arrow{display:flex;align-items:center;justify-content:center;width:54px;height:50px;border:1px solid #bac4cc;border-radius:3px;color:#526a7a}.page-arrow svg{width:25px;height:25px}.page-arrow.disabled{opacity:.22}.page-position{font:12px monospace;color:#7b8993}.empty-cases{padding:30px;font-size:13px;color:#6f7b85}.case-card img{aspect-ratio:5/4;mix-blend-mode:multiply}.case-card{content-visibility:auto;contain-intrinsic-size:auto 350px}
@media(max-width:700px){.difficulty-nav{gap:5px;margin:8px 0}.difficulty-choice{min-width:64px}.case-copy small{gap:5px}.case-copy small .stars{font-size:11px}.catalog-pager{margin:20px 0 5px}}
.empty-cases{display:flex;align-items:center;justify-content:center;gap:20px;min-height:160px;grid-column:1/-1}.empty-cases svg{width:40px;height:40px}.header-reference .stars{font-size:11px;letter-spacing:2px}
.build-header h1{min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.header-reference{flex:none}.difficulty-choice.disabled{opacity:.24;pointer-events:none}