:root{color-scheme:light;--ink:#18332f;--muted:#637873;--accent:#087f78;--accent-dark:#06665f;--accent-soft:#e8f4f0;--line:#dce5e1;--surface:#fff;--page:#f2f5f4;--radius:18px;font-family:"Segoe UI","Microsoft YaHei UI","Microsoft YaHei","PingFang SC",sans-serif;font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased}
*{box-sizing:border-box}body{margin:0;background:var(--page);color:var(--ink);font-size:14px;line-height:1.65}button,input,a{-webkit-tap-highlight-color:transparent}button,input{font:inherit}button{cursor:pointer;color:inherit}button:disabled{cursor:wait;opacity:.48}button svg{width:18px;height:18px;flex-shrink:0;stroke:currentColor;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round}button:focus-visible,a:focus-visible,summary:focus-visible,input:focus-visible,[tabindex]:focus-visible{outline:3px solid #13a598;outline-offset:4px}a{color:var(--accent-dark);text-underline-offset:3px}button{transition:background .16s ease,border-color .16s ease,color .16s ease,box-shadow .16s ease}button:active{transform:translateY(1px)}[hidden]{display:none!important}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.skip-link{position:fixed;z-index:100;top:10px;left:16px;padding:12px 20px;border-radius:8px;background:var(--ink);color:#fff;transform:translateY(-150%)}.skip-link:focus{transform:translateY(0)}
.app-shell{width:min(1580px,100%);padding:24px 34px 18px;margin:0 auto}.masthead{display:flex;justify-content:space-between;align-items:center;gap:16px;margin-bottom:22px}.publication-brand{display:flex;align-items:center;gap:10px;font-size:13px;font-weight:650;letter-spacing:.5px}.brand-mark{width:30px;height:30px;display:grid;place-items:center;border-radius:8px;background:var(--ink);color:#e3fff5}.brand-mark svg{width:21px;stroke:currentColor;stroke-width:1.4;stroke-linecap:round}.brand-divider{display:inline-block;color:#a1b0ab;font-weight:400;margin:0 11px}.edition-label{display:flex;align-items:center;gap:12px;font-size:11px;letter-spacing:1px;color:var(--muted)}.edition-dot{width:4px;height:4px;border-radius:50%;background:#9fb2ab}.heading-row{display:flex;align-items:center;justify-content:space-between;gap:20px}.title-line{display:flex;align-items:baseline;gap:18px}.title-line h1{margin:0;font-weight:700;font-size:32px;line-height:1.3;letter-spacing:-1px}.title-model{font-size:24px;line-height:1.3;letter-spacing:-.7px;color:#82958e;font-weight:450}.page-description{margin:7px 0 0;color:var(--muted);font-size:13px;letter-spacing:.2px}.model-tags{display:flex;flex-wrap:wrap;justify-content:flex-end;gap:8px}.model-tags>span{display:flex;align-items:center;gap:4px;border:1px solid var(--line);border-radius:6px;padding:4px 9px;color:#526a62;font-size:11px;background:#f8faf9;white-space:nowrap;font-weight:600}.model-tags>.verified-tag{border-color:#cde3d9;color:var(--accent-dark);background:#e6f2eb}.verified-tag svg{width:14px;height:14px;stroke:currentColor;stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round}
.section-bar{display:flex;align-items:center;justify-content:space-between;gap:20px;margin-top:24px;margin-bottom:17px;border-bottom:1px solid #d5dfda}.lesson-tabs{display:flex;align-items:stretch;gap:26px}.lesson-tab{position:relative;padding:0 1px 13px;min-height:43px;border:0;background:transparent;color:#72867e;font-size:14px;font-weight:650;display:flex;align-items:center;gap:8px}.lesson-tab.active,.lesson-tab[aria-selected=true]{color:var(--accent-dark)}.lesson-tab.active:after,.lesson-tab[aria-selected=true]:after{content:"";height:3px;position:absolute;bottom:-1px;left:0;right:0;background:var(--accent);border-radius:3px 3px 0 0}.tab-number{font-size:11px;font-variant-numeric:tabular-nums;color:#91a29a;font-weight:500}.lesson-tab.active .tab-number,.lesson-tab[aria-selected=true] .tab-number{color:var(--accent)}.section-caption{display:flex;align-items:center;gap:7px;align-self:flex-start;padding-top:6px;font-size:11px;color:#81958c;letter-spacing:1px}.small-dot{height:5px;width:5px;background:#87a69b;border-radius:50%}
.hardware-layout{display:grid;grid-template-columns:minmax(0,1fr) 340px;gap:20px;align-items:start}.stage-column{min-width:0}.stage-card{background:var(--surface);border:1px solid #d8e2dd;border-radius:var(--radius);overflow:hidden;box-shadow:0 6px 18px #163e2e04}.stage-heading{display:flex;align-items:center;justify-content:space-between;min-height:53px;padding:12px 20px;gap:12px;border-bottom:1px solid #e5ece8;background:#ffffff}.stage-heading-copy{display:flex;align-items:center;gap:8px;color:#61786d;font-size:11px;line-height:1.5}.status-dot{width:6px;height:6px;border-radius:50%;background:#139e7a;box-shadow:0 0 0 3px #eaf7ef;flex-shrink:0}.label-toggle{display:flex;align-items:center;gap:7px;font-size:11px;cursor:pointer;user-select:none;white-space:nowrap;color:#647b70;position:relative}.label-toggle input{position:absolute;opacity:0;width:29px;height:20px;left:0;margin:0}.toggle-track{display:inline-block;position:relative;width:27px;height:16px;border-radius:15px;background:#b6c5be;transition:background .2s}.toggle-track:after{content:"";position:absolute;top:3px;left:3px;width:10px;height:10px;border-radius:50%;background:#fff;transition:transform .2s}.label-toggle input:checked+.toggle-track{background:var(--accent)}.label-toggle input:checked+.toggle-track:after{transform:translateX(11px)}.label-toggle input:focus-visible+.toggle-track{outline:3px solid #13a598;outline-offset:4px}.model-viewport{position:relative;height:clamp(400px,47vh,590px);min-height:400px;width:100%;background:radial-gradient(ellipse at 50% 44%,#fcfdfc 10%,#edf2ef 84%);isolation:isolate;outline-offset:-4px!important;touch-action:none;overflow:hidden}.model-viewport canvas{position:absolute;inset:0;display:block;width:100%;height:100%;z-index:1;touch-action:none}.viewport-identification{position:absolute;z-index:2;top:21px;left:23px;display:flex;flex-direction:column;gap:3px;pointer-events:none}.viewport-identification span:first-child{font-size:11px;font-weight:700;letter-spacing:2px;color:#789a8c}.viewport-identification span:last-child{font-size:9px;letter-spacing:.7px;color:#a1b1a9}.viewport-bottom{position:absolute;z-index:3;bottom:15px;left:20px;right:20px;display:flex;justify-content:space-between;align-items:center;gap:12px;pointer-events:none}.gesture-hint{display:flex;align-items:center;gap:6px;color:#7a9185;font-size:10px;white-space:nowrap}.gesture-hint svg{width:15px;height:15px;stroke:currentColor;stroke-width:1.25}.hint-divider{padding:0 6px;color:#9aac9f}.touch-hint{display:none}.pose-label{background:#ffffffb8;border:1px solid #dbe4dd;border-radius:5px;padding:3px 7px;max-width:52%;font-size:10px;color:#667f70;line-height:1.5;text-align:right;backdrop-filter:blur(8px)}
.hotspots{position:absolute;inset:0;z-index:4;pointer-events:none;overflow:hidden}.hotspots button,.hotspot{position:absolute;pointer-events:auto;border:1px solid #c2d8cd;background:#fffffff2;color:#28594b;border-radius:7px;min-height:34px;padding:6px 10px;font-size:11px;font-weight:600;box-shadow:0 3px 10px #19462d12;white-space:nowrap;backdrop-filter:blur(8px);transform:translate(-50%,-50%);line-height:1.5}.hotspots button:before,.hotspot:before{content:"";display:inline-block;vertical-align:middle;width:5px;height:5px;border-radius:50%;margin-right:6px;background:var(--accent)}.hotspots button:hover,.hotspots button.active,.hotspots button.is-active,.hotspots button[aria-pressed=true],.hotspot.active,.hotspot.is-active{border-color:var(--accent);background:var(--accent);color:white;box-shadow:0 3px 14px #076d4b22}.hotspots button:hover:before,.hotspots button.active:before,.hotspots button.is-active:before,.hotspots button[aria-pressed=true]:before{background:#acffe6}.hotspots button:active,.hotspot:active{transform:translate(-50%,-50%)}.hotspot-label{font:inherit}
.loading-overlay{position:absolute;inset:0;z-index:6;display:flex;flex-direction:column;align-items:center;justify-content:center;background:radial-gradient(ellipse at center,#f8fbf9,#eef4f0);gap:9px;text-align:center;padding:24px;color:#698177}.loading-overlay strong{margin-top:12px;color:#355b4c;font-size:16px;font-weight:600}.loading-overlay>span{font-size:12px}.loading-object{display:flex;gap:5px;align-items:flex-end;height:43px}.loading-object span{height:35px;width:17px;border:1px solid #a9c8b6;background:#d7e9dd;border-radius:3px;animation:loading-bars 1.5s ease-in-out infinite}.loading-object span:nth-child(2){height:43px;animation-delay:.15s}.loading-object span:nth-child(3){height:30px;animation-delay:.3s}@keyframes loading-bars{0%,100%{transform:translateY(0);opacity:.7}50%{transform:translateY(-7px);opacity:1}}.viewer-error{position:absolute;inset:0;z-index:7;display:flex;flex-direction:column;align-items:center;justify-content:center;background:#f5f8f5;text-align:center;padding:34px}.error-symbol{display:grid;place-items:center;border:1px solid #ccb98c;border-radius:50%;width:38px;height:38px;background:#f4efdf;color:#87703f;font-size:22px}.viewer-error h2{font-size:20px;margin:15px 0 8px}.viewer-error p{max-width:310px;margin:0 0 20px;color:var(--muted);font-size:13px}.primary-button{border:1px solid var(--accent);border-radius:8px;background:var(--accent);color:#fff;padding:10px 18px;min-height:42px}
.camera-toolbar{display:flex;align-items:center;gap:10px;padding:7px 18px;border-top:1px solid #e0e8e2;border-bottom:1px solid #e0e8e2;background:#f9fbf9}.toolbar-label{color:#8a9b92;font-size:11px;min-width:26px;white-space:nowrap}.view-buttons{display:flex;gap:3px;flex:1}.view-buttons button{background:none;border:1px solid transparent;border-radius:6px;min-width:46px;min-height:36px;padding:5px 9px;color:#647d6e;font-size:11px}.view-buttons button:hover{background:#e9f2ec;color:var(--accent-dark)}.view-buttons button.active,.view-buttons button[aria-pressed=true]{color:var(--accent-dark);border-color:#c4ddd0;background:#e6f1e9;font-weight:600}.icon-button{border:1px solid transparent;border-radius:6px;background:transparent;width:36px;height:36px;display:grid;place-items:center;color:#6d8376}.icon-button:hover{background:#e8f1eb;color:var(--accent-dark)}.animation-controls{padding:14px 19px 15px;display:flex;flex-direction:column;gap:11px}.cover-control-row,.explode-control-row{display:flex;align-items:center;justify-content:space-between;gap:12px}.control-group{display:flex;align-items:center;gap:7px;flex-shrink:0}.control-group .toolbar-label{margin-right:4px}.control-group button{display:flex;align-items:center;justify-content:center;gap:6px;min-height:40px;background:#fff;border:1px solid #d6e2d9;border-radius:7px;padding:8px 11px;color:#456753;font-size:12px;white-space:nowrap}.control-group button:hover{background:#f0f7f1;border-color:#a2cbb6;color:#16684a}.control-group button[aria-pressed=true],.control-group button.active{background:#e7f4eb;border-color:#92c5a9;color:#086649}.control-group button svg{width:16px;height:16px}.text-button{border:0;background:transparent;display:flex;align-items:center;justify-content:center;gap:5px;min-height:40px;padding:7px 0 7px 8px;color:#849789;font-size:11px;white-space:nowrap}.text-button:hover{color:var(--accent-dark)}.text-button svg{width:14px;height:14px}.range-control{display:flex;gap:8px;align-items:center;flex:1;min-width:85px;margin:0 4px}.range-end{font-size:10px;color:#8c9e91;white-space:nowrap}input[type=range]{width:100%;min-width:40px;height:32px;background:transparent;cursor:pointer;accent-color:var(--accent);margin:0}input[type=range]::-webkit-slider-runnable-track{height:4px;background:#dce8df;border-radius:4px}input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;margin-top:-5px;width:14px;height:14px;border-radius:50%;background:var(--accent)}input[type=range]{-webkit-appearance:none;appearance:none}input[type=range]::-moz-range-track{height:4px;background:#dce8df;border-radius:4px}input[type=range]::-moz-range-thumb{width:14px;height:14px;background:var(--accent);border:0;border-radius:50%}.pause-button{display:flex;align-items:center;justify-content:center;gap:4px;border:1px solid #dce6de;border-radius:7px;background:#f7faf7;padding:8px 9px;min-height:40px;font-size:11px;color:#78907e;white-space:nowrap}.pause-button:hover{color:var(--accent-dark);border-color:#b5d3bf}.pause-button[aria-pressed=true]{color:var(--accent-dark);background:#e6f3e9}.pause-button svg{width:13px;height:13px}.stage-footnote{display:flex;align-items:flex-start;gap:6px;color:#809387;font-size:11px;padding:11px 4px}.stage-footnote svg{width:15px;height:15px;stroke:currentColor;stroke-width:1.3;flex-shrink:0;margin-top:2px}
.lesson-panel{background:#fff;border:1px solid #dbe4dd;border-radius:var(--radius);overflow:hidden;box-shadow:0 6px 18px #163e2e04}.topic-navigation{padding:19px 20px 17px;border-bottom:1px solid #e0e9e2;background:#fcfdfb}.panel-section-label{display:flex;align-items:center;justify-content:space-between;margin-bottom:12px;font-size:12px;color:#536f5e;font-weight:650}.navigation-hint{color:#9ca99d;font-size:10px;font-weight:400}#topic-list{display:flex;flex-wrap:wrap;gap:6px}#topic-list button{border:1px solid #e1e8e0;background:white;border-radius:6px;min-height:36px;padding:7px 10px;text-align:left;color:#6c816e;line-height:1.35;font-size:11px;flex:0 1 auto}#topic-list button:hover{border-color:#a8c9b2;background:#f1f8f2;color:#346248}#topic-list button.active,#topic-list button[aria-current=true],#topic-list button[aria-pressed=true],#topic-list button[aria-selected=true]{background:#e5f2e8;color:#17664b;border-color:#abcdb4;font-weight:650}#topic-list button small{font-size:9px;color:inherit;opacity:.7}#topic-list button svg{width:13px;height:13px;vertical-align:middle;margin-right:4px}.lesson-content{padding:23px 23px 21px}.lesson-eyebrow{margin:0 0 7px;color:#7a9b85;font-size:10px;letter-spacing:1px;text-transform:uppercase;font-weight:600}.lesson-content h2{margin:0 0 9px;font-size:23px;font-weight:680;letter-spacing:-.5px;line-height:1.4;color:#264c36}.lesson-summary{font-size:13px;line-height:1.85;color:#6f8372;margin:0 0 19px}.lesson-facts{display:flex;flex-direction:column;gap:18px}.lesson-fact h3{display:flex;align-items:center;gap:7px;font-size:11px;color:#527658;letter-spacing:.3px;margin:0 0 6px;font-weight:650}.fact-icon{width:19px;height:19px;display:grid;place-items:center;background:#eef4ec;border:1px solid #dfe9db;border-radius:4px;color:#81a07c;font-size:8px;font-weight:600;letter-spacing:0}.lesson-fact p{margin:0;font-size:12px;color:#6a816b;line-height:1.85}.example-fact{background:#f1f7ee;border:1px solid #e3eddc;border-radius:9px;padding:13px 14px}.example-fact h3{color:#59744d}.example-fact h3 svg{width:15px;height:15px;stroke:currentColor;stroke-width:1.3}.example-fact p{color:#6a805f;font-size:12px}.lesson-notes{margin-top:16px;color:#93a18e;font-size:10px;line-height:1.8;padding-left:10px;border-left:2px solid #d9e5d0}.lesson-notes:empty{display:none}.lesson-notes ul{padding-left:14px;margin:0}.lesson-notes li+li{margin-top:3px}.source-link{display:inline-flex;align-items:center;gap:5px;font-size:10px;margin-top:18px;color:#7c9471;text-decoration:none}.source-link:hover{text-decoration:underline;color:var(--accent-dark)}.source-link svg{width:12px;height:12px;stroke:currentColor;stroke-width:1.25}.lesson-panel .badge{font-size:10px;padding:2px 5px;border-radius:4px;background:var(--accent-soft);color:var(--accent)}
.page-footer{display:flex;justify-content:space-between;align-items:flex-start;gap:24px;border-top:1px solid #dbe4da;margin-top:12px;padding:13px 2px 0;color:#92a28c;font-size:10px}.source-details{max-width:850px}.source-details summary{display:flex;align-items:center;gap:6px;min-height:24px;cursor:pointer;list-style:none;color:#889d82}.source-details summary::-webkit-details-marker{display:none}.source-details summary>svg{width:14px;height:14px;stroke:currentColor;stroke-width:1.2}.disclosure-plus{font-size:15px;line-height:1;margin-left:5px}.source-details[open] .disclosure-plus{transform:rotate(45deg)}.source-details-body{padding:8px 0;color:#839879;font-size:11px;line-height:1.9}.source-details-body p{margin:0 0 8px}.source-details-body a{display:inline-block;color:#627f54;margin-right:17px}.footer-model{white-space:nowrap;padding-top:4px;letter-spacing:.4px;color:#a0af95}.footer-model span{margin:0 6px}
@media(min-width:1600px){.app-shell{padding-top:30px}.hardware-layout{grid-template-columns:minmax(0,1fr) 360px}.model-viewport{height:550px}.lesson-content{padding:25px}.lesson-summary,.lesson-fact p{font-size:13px}#topic-list button{font-size:12px}.lesson-content h2{font-size:25px}.stage-heading-copy,.label-toggle,.control-group button{font-size:12px}}
@media(max-width:1200px){.app-shell{padding:22px 24px 16px}.hardware-layout{grid-template-columns:minmax(0,1fr) 315px;gap:16px}.topic-navigation{padding:17px 17px 15px}.lesson-content{padding:20px}.control-group button{padding:8px 9px;font-size:11px}.animation-controls{padding:13px 15px}.control-group{gap:5px}.range-control{gap:5px;margin:0}.camera-toolbar{padding:7px 14px;gap:6px}.view-buttons button{min-width:39px;padding:5px 7px}.pause-button{padding:8px 7px}.gesture-hint{font-size:9px}.pose-label{font-size:9px}.viewport-bottom{left:16px;right:16px}.model-tags{gap:5px}.model-tags>span{font-size:10px;padding:4px 7px}}
@media(max-width:1000px){.hardware-layout{grid-template-columns:minmax(0,1fr) 290px;gap:14px}.app-shell{padding:20px 18px 14px}.masthead{margin-bottom:18px}.title-line h1{font-size:29px}.title-model{font-size:21px}.model-tags>span:first-child{display:none}.cover-control-row{gap:6px}.control-group{gap:4px}.control-group .toolbar-label{margin-right:0}.control-group button{padding:7px 8px;font-size:10px;gap:4px}.control-group button svg{width:13px;height:13px}.animation-controls{padding:12px}.text-button{font-size:10px}.explode-control-row{gap:7px}.pause-button{font-size:0;padding:8px;min-width:35px}.pause-button svg{width:14px;height:14px}.pause-button span{display:none}.range-end{font-size:9px}.camera-toolbar{gap:5px}.view-buttons{gap:0}.view-buttons button{min-width:34px;padding:5px 6px;font-size:10px}.toolbar-label{min-width:24px;font-size:10px}.icon-button{width:30px}.pose-label{max-width:45%}.gesture-hint{white-space:normal;max-width:52%}.topic-navigation{padding:16px 15px}.lesson-content{padding:19px 17px}.lesson-content h2{font-size:22px}.lesson-summary{font-size:12px}.lesson-fact p{font-size:11px}.lesson-facts{gap:15px}#topic-list{gap:5px}#topic-list button{font-size:10px;padding:6px 8px}.viewport-identification{left:18px;top:18px}.stage-heading{padding:12px 15px}.model-viewport{height:435px;min-height:400px}}
@media(max-width:820px){.hardware-layout{grid-template-columns:1fr;gap:12px}.app-shell{max-width:760px;padding:18px 20px}.model-viewport{height:clamp(380px,56vw,490px);min-height:380px}.lesson-panel{display:grid;grid-template-columns:230px minmax(0,1fr)}.topic-navigation{border-bottom:0;border-right:1px solid #e0e9e2;padding:22px 18px}.lesson-content{padding:22px}.lesson-summary,.lesson-fact p{font-size:13px}#topic-list button{font-size:11px;min-height:38px}.lesson-content h2{font-size:24px}.section-caption{font-size:10px}.control-group button{padding:9px 12px;font-size:12px;gap:6px}.control-group{gap:7px}.control-group button svg{width:16px;height:16px}.animation-controls{padding:15px 19px}.text-button{font-size:11px}.toolbar-label{font-size:11px;min-width:28px}.view-buttons button{min-width:45px;font-size:11px}.camera-toolbar{padding:7px 18px}.range-end{font-size:10px}.pause-button{font-size:11px;gap:4px}.pause-button span{display:inline}.range-control{margin:0 5px}.viewport-bottom{left:20px;right:20px}.gesture-hint{font-size:10px}.pose-label{font-size:10px}.stage-footnote{padding-bottom:5px}.page-footer{margin-top:18px}.lesson-notes,.source-link{font-size:11px}.lesson-fact h3{font-size:12px}.heading-row{gap:12px}.model-tags{gap:6px}}
@media(max-width:580px){body{font-size:14px}.app-shell{padding:16px 12px 16px}.masthead{margin-bottom:18px}.publication-brand{font-size:11px;gap:8px}.brand-mark{width:27px;height:27px;border-radius:7px}.brand-divider{margin:0 8px}.edition-label{font-size:9px;gap:6px;letter-spacing:0}.edition-dot{display:none}.heading-row{align-items:flex-start}.title-line{display:block}.title-line h1{font-size:29px;letter-spacing:-.7px}.title-model{display:block;font-size:17px;margin-top:3px;letter-spacing:.2px}.page-description{font-size:11px;margin-top:7px}.model-tags{flex-direction:column;align-items:flex-end;gap:6px;padding-top:3px}.model-tags>span{font-size:10px;padding:3px 7px}.section-bar{margin-top:19px;margin-bottom:13px}.lesson-tabs{gap:26px}.lesson-tab{font-size:13px;min-height:43px;padding-bottom:11px;gap:6px}.section-caption{font-size:9px;letter-spacing:0;padding-top:7px}.section-caption .small-dot{display:none}.stage-card{border-radius:14px}.stage-heading{min-height:47px;padding:11px 13px}.stage-heading-copy{font-size:10px;gap:7px}.label-toggle{font-size:10px}.model-viewport{height:390px;min-height:360px}.viewport-identification{left:16px;top:17px}.viewport-identification span:first-child{font-size:9px}.viewport-identification span:last-child{font-size:8px}.viewport-bottom{left:13px;right:13px;bottom:13px;gap:8px}.gesture-hint{font-size:9px;max-width:49%}.gesture-hint svg{display:none}.touch-hint{display:inline}.hint-divider{padding:0 3px}.pose-label{font-size:9px;padding:3px 5px;max-width:49%}.camera-toolbar{padding:5px 10px;gap:4px}.toolbar-label{font-size:10px;min-width:24px}.view-buttons{justify-content:space-between}.view-buttons button{font-size:10px;min-width:34px;min-height:40px;padding:6px 5px}.icon-button{width:32px;height:40px}.animation-controls{padding:12px 12px 14px;gap:11px}.control-group{gap:5px}.control-group button{font-size:11px;padding:8px 8px;min-height:40px;gap:5px}.control-group button svg{width:14px;height:14px}.cover-control-row{gap:3px}.text-button{font-size:10px;gap:3px;padding-left:4px}.text-button svg{width:12px;height:12px}.explode-control-row{gap:8px;flex-wrap:wrap}.explode-control-row>.control-group{order:0}.range-control{order:2;flex-basis:100%;margin:0;gap:10px;padding-left:29px}.pause-button{order:1;font-size:10px;min-height:40px;padding:8px}.range-end{font-size:10px}.stage-footnote{font-size:10px;padding:10px 4px 2px;gap:5px}.lesson-panel{display:block;border-radius:14px}.topic-navigation{padding:18px 17px;border-right:0;border-bottom:1px solid #e0e9e2}.panel-section-label{font-size:12px;margin-bottom:11px}.navigation-hint{font-size:10px}#topic-list{gap:7px}#topic-list button{font-size:11px;min-height:40px;padding:8px 11px}.lesson-content{padding:22px 20px}.lesson-content h2{font-size:24px}.lesson-summary{font-size:13px;line-height:1.85;margin-bottom:21px}.lesson-facts{gap:20px}.lesson-fact p{font-size:13px;line-height:1.9}.lesson-notes,.source-link{font-size:11px}.example-fact{padding:14px}.hotspots button,.hotspot{min-height:32px;font-size:10px;padding:5px 7px;border-radius:5px}.page-footer{display:block;font-size:10px;margin-top:16px;padding-top:11px}.footer-model{display:block;margin-top:9px;font-size:9px}.source-details-body{font-size:10px}.source-details-body a{margin-right:12px}}
@media(max-width:360px){.app-shell{padding-left:9px;padding-right:9px}.edition-label{display:none}.section-caption{display:none}.model-viewport{height:360px}.control-group button{font-size:10px;padding:8px 7px}.text-button{font-size:9px}.view-buttons button{min-width:31px;font-size:9px}.camera-toolbar{padding:5px 8px;gap:2px}.toolbar-label{min-width:22px}.control-group{gap:4px}.animation-controls{padding:11px 10px}.model-tags{gap:5px}.model-tags>span{font-size:9px}.title-model{font-size:16px}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}}
@media print{body{background:white}.app-shell{max-width:none;padding:0}.masthead,.section-bar,.animation-controls,.camera-toolbar,.stage-footnote,.page-footer,.label-toggle,.viewport-bottom{display:none}.hardware-layout{display:block}.stage-card{break-inside:avoid}.model-viewport{height:400px}.lesson-panel{margin-top:20px;display:block}.topic-navigation{display:none}.lesson-content{padding:20px}#principle-panel{break-before:page}}
  
/* Keep instructional copy and interactive targets comfortable at teaching distance. */
.lesson-summary,.lesson-fact p,.example-fact p{font-size:14px;color:#586f5b}
.lesson-fact h3{font-size:12px;color:#41664c}
.lesson-notes{font-size:11px;color:#6d8067}
.source-link{font-size:11px;color:#56774e}
.stage-heading-copy,.label-toggle,.toolbar-label,.navigation-hint,.gesture-hint,.stage-footnote{color:#657d6b}
.view-buttons button{min-height:40px;color:#526d5b}
.icon-button{min-width:40px;min-height:40px}
#topic-list button{font-size:12px;min-height:40px;color:#526b55}
#topic-list button.is-active,#topic-list button[aria-current=page]{background:#e5f2e8;color:#17664b;border-color:#abcdb4;font-weight:650}
.hotspots button,.hotspot{min-height:40px;font-size:12px}
.control-group button{font-size:12px}
.text-button,.pause-button{font-size:11px;color:#59735e}
.range-end{color:#647e6c}
.source-details summary,.source-details-body{color:#637b5b}
@media(max-width:580px){.lesson-summary,.lesson-fact p,.example-fact p{font-size:14px}.control-group button{font-size:11px}.view-buttons button{font-size:10px;min-width:32px}.hotspots button,.hotspot{font-size:11px}#topic-list button{font-size:12px}.text-button{font-size:10px}.pause-button{font-size:10px}.icon-button{min-width:36px}.lesson-notes,.source-link{font-size:12px}}
/* Compact numbered pins keep dense terminal groups legible. */
.topic-number{display:inline-block;margin-right:7px;font-variant-numeric:tabular-nums;opacity:.6}
.hotspots .hotspot{width:30px;height:30px;min-height:30px;padding:0;display:flex;align-items:center;justify-content:center;border-radius:50%;font-size:11px;background:#fffffff5;border:1.5px solid #5b9585}
.hotspots .hotspot:before{display:none}
.hotspot-number{font-variant-numeric:tabular-nums}
.hotspot .hotspot-label{display:none;position:absolute;left:38px;top:50%;transform:translateY(-50%);background:#fff;color:#175b4a;border:1px solid #91b6a7;padding:6px 9px;border-radius:6px;box-shadow:0 3px 12px #163c2920;pointer-events:none;white-space:nowrap}
.hotspot:hover .hotspot-label,.hotspot:focus-visible .hotspot-label,.hotspot.is-active .hotspot-label{display:block}
.hotspot.is-active{z-index:10}
@media(max-width:580px){.hotspots .hotspot{width:28px;height:28px;min-height:28px;font-size:10px}.hotspot.is-active .hotspot-label{left:50%;top:34px;transform:translateX(-50%);font-size:10px}}