:root{font-family:Inter,"Segoe UI","Microsoft YaHei",sans-serif;color:#173d49;background:#eff3f0;font-synthesis:none;--teal:#246858;--line:#d8e1da;--muted:#617771}*{box-sizing:border-box}body{margin:0}button,select,input{font:inherit}button{cursor:pointer;color:inherit;border:1px solid var(--line);border-radius:9px;background:#fff;padding:10px 15px;min-height:42px;transition:background .15s,transform .15s}button:hover{background:#e1ede4}button:active{transform:translateY(1px)}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,canvas:focus-visible{outline:3px solid #d3a044;outline-offset:3px}button:disabled{opacity:.45;cursor:default}header{display:flex;align-items:center;justify-content:space-between;max-width:1600px;padding:20px 36px;margin:auto;border-bottom:1px solid var(--line)}.brand{color:inherit;display:flex;align-items:center;gap:12px;text-decoration:none;font-size:21px;font-weight:750;letter-spacing:2px}.brandmark{background:#173f42;color:#d5eeb1;font-size:39px;border-radius:12px;width:49px;height:49px;text-align:center;line-height:43px}.brand small{display:block;font-size:9px;font-weight:500;letter-spacing:2px;margin-top:5px}.header-actions{display:flex;align-items:center;gap:12px}.edition{font-size:13px;color:var(--muted);margin-right:16px}#help{width:43px;padding:0;border-radius:50%;font-weight:700}main{max-width:1600px;padding:22px 36px 10px;margin:auto}.intro{display:flex;align-items:end;justify-content:space-between;margin-bottom:22px}.eyebrow{font-size:11px;letter-spacing:1.5px;color:#61806e;font-weight:700}.intro h1{font-size:30px;letter-spacing:1px;margin:7px 0 0;font-weight:600}.intro p{font-size:14px;color:var(--muted);margin:0 0 5px}nav{display:grid;grid-template-columns:repeat(5,1fr);gap:8px;margin-bottom:16px}nav button{text-align:left;position:relative;background:transparent;border:1px solid #d6dfd9;font-size:15px;font-weight:700;padding:13px 15px;min-height:66px}nav button b{font-size:11px;color:#75918a;margin-right:9px;font-weight:500}nav button span{display:block;font-size:11px;font-weight:400;color:#6d817b;margin-left:24px;margin-top:5px}nav button[aria-pressed=true]{background:#193f43;color:#fff;border-color:#193f43}nav button[aria-pressed=true] b,nav button[aria-pressed=true] span{color:#bcdaa8}.workspace{display:grid;grid-template-columns:minmax(0,1fr) 314px;gap:18px;align-items:start}.lab{background:#fff;border-radius:17px;border:1px solid var(--line);overflow:hidden}.scene{height:480px;min-height:360px;position:relative;background:radial-gradient(ellipse at 55% 40%,#245563 0%,#102e3b 60%,#0c2430 100%);isolation:isolate;overflow:hidden;color:#e6f2ec}.scene canvas{width:100%;height:100%;display:block;touch-action:none}.scene-heading{position:absolute;top:21px;left:23px;display:flex;gap:9px;align-items:center;font-size:13px;pointer-events:none}.live-dot{background:#b9dd94;width:6px;height:6px;border-radius:50%;box-shadow:0 0 9px #b9dd94}.scene-tag{font-size:10px;color:#adc2c5;border:1px solid #52717c;border-radius:5px;padding:3px 6px;margin-left:5px}.scene-tools{position:absolute;right:16px;top:14px;display:flex;gap:5px}.scene-tools button{background:#123542cc;color:#c7dedc;border-color:#3c5a67;font-size:11px;padding:8px;min-height:35px}.scene-tools button:hover{background:#37626c}.compartment{position:absolute;left:25px;display:flex;gap:9px;align-items:center;pointer-events:none}.compartment i{width:3px;height:35px;background:#77d3e2;border-radius:3px}.compartment small{display:block;font-size:8px;letter-spacing:1.7px;color:#89aab4;margin-top:5px}.compartment strong{font-size:21px;font-weight:400;margin-left:10px;font-variant-numeric:tabular-nums}.outer{top:95px}.inner{bottom:81px}.inner i{background:#cfce8d}.floating-label{position:absolute;background:#143541e6;border:1px solid #718b9299;border-radius:5px;padding:6px 9px;font-size:11px;pointer-events:none;transform:translate(-50%,-100%);white-space:nowrap}.cargo-label{border-color:#e4bb7477;color:#f9d5a1}.legend{position:absolute;bottom:19px;left:23px;display:flex;gap:13px;font-size:10px;color:#b7cfd1;pointer-events:none}.legend span{display:flex;align-items:center;gap:5px}.legend i{height:7px;width:7px;border-radius:50%;display:inline-block}.legend em{font-style:normal}.lipid{background:#7ecca9}.tail{background:#4a9eac}.solute{background:#eac486}.orbit-hint{position:absolute;bottom:18px;right:17px;color:#8cafb5;font-size:10px;pointer-events:none}.transport-strip{padding:17px 22px 19px}.stage-caption{display:flex;align-items:center;gap:12px;min-height:25px}.stage-caption>span:first-child{font-size:11px;font-variant-numeric:tabular-nums;color:#72897c}.stage-caption strong{font-size:14px;font-weight:600}.stage-caption>span:last-child{font-size:10px;color:#697b74;margin-left:auto}.timeline{display:flex;gap:5px;margin:12px 0 15px}.timeline i{height:3px;background:#e4e9e5;flex:1;border-radius:3px}.timeline i.done{background:#5c9175}.playbar{display:flex;gap:8px}.primary{background:#d0e5b4;border-color:#d0e5b4;color:#203d33;font-weight:700;min-width:125px}.primary:hover{background:#bfd89d}.speed{margin-left:auto;display:flex;gap:9px;align-items:center;font-size:11px;color:#6c7f77}select{background:#fff;border:1px solid var(--line);border-radius:6px;padding:6px;color:inherit;min-height:35px}aside{background:#f9fbf7;border:1px solid var(--line);border-radius:17px;overflow:hidden}.question{padding:20px 21px;background:#e5eddf;border-bottom:1px solid var(--line)}.question h2{font-size:18px;line-height:1.6;margin:9px 0 0;font-weight:600}.controls,.readout{padding:18px 21px}.section-title{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-bottom:15px}.section-title h3{font-size:13px;margin:0}.section-title>span{font-size:10px;color:#76857a}.control-heading{display:flex;justify-content:space-between;align-items:center;font-size:12px;margin-top:10px}output{background:#e7ede6;padding:2px 6px;border-radius:4px;font-size:12px;min-width:31px;text-align:center}input[type=range]{accent-color:#397461;width:100%;height:21px;margin:5px 0 0;cursor:pointer}.presets{display:flex;gap:7px;margin-top:8px}.presets button{font-size:11px;flex:1;padding:7px 6px;min-height:34px}.small-note{font-size:10px;color:#718377;line-height:1.7;margin:8px 0 12px}.switch-row{display:flex;align-items:center;position:relative;gap:9px;border-top:1px solid #e3e8e0;padding:12px 0 4px;margin-top:8px;font-size:12px;cursor:pointer}.switch-row>span:first-child{flex:1}.switch-row small{display:block;font-size:10px;color:#728378;margin-top:4px;line-height:1.4}.switch-row input{position:absolute;right:0;opacity:0;width:38px;height:28px;cursor:pointer}.switch{width:33px;height:20px;border-radius:20px;background:#bac6bd;position:relative;pointer-events:none}.switch:after{content:'';height:14px;width:14px;position:absolute;top:3px;left:3px;background:white;border-radius:50%;transition:transform .2s}.switch-row input:checked+.switch{background:#397461}.switch-row input:checked+.switch:after{transform:translateX(13px)}.switch-row input:focus-visible+.switch{outline:3px solid #d3a044}.switch-row input:disabled+.switch{opacity:.4}.type-row{display:flex;align-items:center;justify-content:space-between;font-size:11px;margin:12px 0}.type-row[hidden]{display:none}.readout{border-top:1px solid var(--line);background:#fff}.metrics{display:grid;grid-template-columns:1fr 1fr;gap:7px}.metrics small{font-size:10px;color:#687f76}.metrics strong{display:block;font-size:23px;font-weight:500;margin-top:5px;font-variant-numeric:tabular-nums}.metrics strong span{font-size:10px;color:#74857d}.readout p{font-size:12px;line-height:1.8;color:#406055;margin:12px 0}.readout button{font-size:11px;width:100%;min-height:34px;background:#f6f8f3}.bulk-note{font-size:13px;line-height:1.9;color:#5d7268;margin:0 0 20px}.records{margin-top:20px;background:white;border:1px solid var(--line);padding:20px;border-radius:14px}.records .section-title button{font-size:11px;min-height:32px;padding:5px 10px}.table-scroll{overflow:auto}table{border-collapse:collapse;width:100%;font-size:12px;line-height:1.7}th,td{text-align:left;padding:12px;border-bottom:1px solid var(--line);min-width:110px}th{font-weight:600;background:#f1f5ee}td small{display:block;color:#748178}footer{display:flex;gap:20px;align-items:center;justify-content:space-between;font-size:10px;color:#718178;margin:14px 0 0}footer button{background:none;border:0;font-size:11px;color:#456c5b;min-height:30px}dialog{border:1px solid #d7e0d4;border-radius:18px;padding:25px;width:min(860px,calc(100% - 28px));max-height:88vh;color:#24483f;background:#fafcf8;box-shadow:0 25px 100px #0d262f55}dialog::backdrop{background:#0d263bcc;backdrop-filter:blur(4px)}.dialog-head{display:flex;justify-content:space-between;align-items:center;gap:15px;margin-bottom:15px}.dialog-head h2{font-size:22px;margin:0}.dialog-head button{padding:5px;width:38px}.dialog-head+div{font-size:14px;line-height:1.9}.dialog-head+div a{color:#17685d}.dialog-head+div li{margin:8px 0}.dialog-head+div .disclosure{font-size:11px;line-height:1.8;color:#6c7f77;background:#edf1e8;padding:12px;border-radius:8px}#fallback{position:absolute;inset:100px 30px;text-align:center;padding:25px;background:#102c3e;z-index:4}.lab:fullscreen{display:flex;flex-direction:column;background:#fff}.lab:fullscreen .scene{height:auto;flex:1}.lab:fullscreen .transport-strip{flex-shrink:0}.lab:fullscreen .scene canvas{position:absolute;inset:0}
@media(min-width:1400px){.scene{height:565px}aside{min-height:694px}.controls{padding-top:22px;padding-bottom:22px}.question{padding-top:24px;padding-bottom:24px}}
@media(max-width:1100px){header{padding:16px 22px}main{padding:20px 22px}.workspace{grid-template-columns:minmax(0,1fr) 286px;gap:12px}.scene{height:500px}.scene-tag{display:none}.orbit-hint{display:none}.scene-heading{left:17px}.legend{gap:9px;left:15px}.scene-tools{right:10px}.controls,.readout{padding:16px}.question{padding:18px}.intro p{font-size:12px}.stage-caption>span:last-child{display:none}.playbar button{padding:9px 11px}.primary{min-width:110px}.speed{gap:4px}}
@media(max-width:900px){header{padding:14px 17px}.brand{font-size:18px}.brandmark{width:40px;height:40px;font-size:32px;line-height:36px}.brand small{font-size:8px;letter-spacing:1px}.edition{display:none}.header-actions{gap:7px}.header-actions button{font-size:11px;padding:8px 10px}#help{width:34px;min-height:34px}main{padding:20px 14px 10px}.intro{display:block;margin-bottom:18px}.intro h1{font-size:25px}.intro p{margin-top:10px;font-size:12px}nav{gap:5px}nav button{padding:10px 3px;text-align:center;font-size:12px;min-height:58px}nav button b{display:block;margin:0 0 4px;font-size:9px}nav button span{display:none}.workspace{grid-template-columns:1fr}.scene{height:390px;min-height:330px}.scene-heading{top:17px;font-size:12px}.scene-tools{top:10px}.compartment{left:17px}.outer{top:72px}.inner{bottom:65px}.compartment strong{font-size:18px}.compartment{font-size:12px}.legend{font-size:9px;bottom:15px}.floating-label{font-size:10px;padding:4px 7px}.transport-strip{padding:15px}.playbar{gap:6px}.playbar button{font-size:12px;padding:10px}.speed{font-size:10px}.speed select{font-size:11px}.question h2{font-size:18px}.controls{padding:18px 20px}.readout{padding:18px 20px}.switch-row{font-size:14px;min-height:50px}.control-heading{font-size:13px}input[type=range]{height:30px}.presets button,.readout button{min-height:40px;font-size:12px}.question{padding:20px}footer{flex-wrap:wrap;gap:0 9px;justify-content:center;font-size:9px}footer>span:last-child{display:none}.records{padding:14px}.scene canvas{touch-action:pan-y}.lab:fullscreen .scene canvas{touch-action:none}}
@media(prefers-reduced-motion:reduce){*{transition:none!important}}
/* Classroom revision: give the scene space by removing repeated headings, not shrinking core controls. */
header{padding:12px 28px}.brandmark{width:42px;height:42px;line-height:37px;font-size:34px}main{padding:14px 28px 8px}.intro{margin-bottom:13px}.intro .eyebrow{display:none}.intro h1{font-size:25px;margin:0}.intro p{font-size:13px;margin:0}nav{margin-bottom:12px}nav button{font-size:18px;min-height:52px;padding:12px}nav button span{display:none}nav button b{font-size:12px}.workspace{grid-template-columns:minmax(0,1fr) 350px;gap:14px}.scene{height:clamp(360px,calc(100vh - 326px),690px)}.transport-strip{padding:12px 18px}.stage-caption strong{font-size:17px}.stage-caption>span:first-child{font-size:12px}.stage-caption>span:last-child{display:none}.playbar button{font-size:16px;min-height:44px}.speed{font-size:13px}.scene-heading{font-size:16px}.scene-tools button{font-size:13px;min-height:40px;padding:8px}.scene-tools{gap:4px}.compartment{font-size:17px}.legend{font-size:12px}.orbit-hint{font-size:12px}.floating-label{font-size:14px;padding:6px 9px}.question{padding:13px 17px}.question h2{font-size:19px;line-height:1.45;margin:6px 0 0}.question .eyebrow{font-size:12px}.controls,.readout{padding:12px 17px}.section-title{margin-bottom:9px}.section-title h3{font-size:16px}.section-title>span{font-size:12px}.controls>.section-title>span{display:none}.slider-row{display:grid;grid-template-columns:70px 1fr 34px;align-items:center;gap:8px;min-height:37px;font-size:15px}.slider-row input{margin:0;height:30px}output{font-size:14px}.presets{margin-top:4px}.presets button{font-size:13px;min-height:37px}.small-note{display:none}.switch-row{padding:8px 0 0;margin-top:8px;font-size:15px;min-height:44px}.switch-row small{font-size:11px;margin-top:2px}.type-row{font-size:14px;margin:8px 0}.readout p{font-size:15px;line-height:1.55;margin:8px 0}.metrics small{font-size:12px}.metrics strong{font-size:23px;margin-top:2px}.metrics strong span{font-size:12px}.readout button{font-size:13px;min-height:36px}.bulk-note{font-size:15px;line-height:1.75;margin:8px 0 16px}.readout .section-title{margin-bottom:8px}aside{min-height:0}footer{margin-top:6px}footer,footer button{font-size:11px}.scene canvas{touch-action:none}.floating-label::after{content:'';position:absolute;left:50%;top:100%;height:15px;width:1px;background:#a0c7be88}.cargo-label::after{background:#ebc58388}
.workspace:is(:fullscreen,.presentation){padding:18px;background:#edf3ed;align-items:stretch;overflow:auto;grid-template-columns:minmax(0,1fr) 360px}.workspace:is(:fullscreen,.presentation) .lab{display:flex;flex-direction:column}.workspace:is(:fullscreen,.presentation) .scene{flex:1;height:auto;min-height:370px}.workspace:is(:fullscreen,.presentation) .scene canvas{position:absolute;inset:0}.workspace:is(:fullscreen,.presentation) aside{align-self:center}.workspace:is(:fullscreen,.presentation) .transport-strip{flex-shrink:0}.workspace:is(:fullscreen,.presentation) .scene-tag{display:none}
@media(max-width:1200px) and (min-width:901px){.workspace{grid-template-columns:minmax(0,1fr) 324px}.scene-heading{top:68px}.scene-tools{top:12px;left:15px;right:auto}.outer{top:118px}.legend{gap:9px;font-size:11px}.playbar button{font-size:15px;padding:9px}.orbit-hint{display:none}.question h2{font-size:18px}}
@media(max-height:820px) and (min-width:901px){header{padding-top:8px;padding-bottom:8px}.brandmark{height:36px;width:36px;line-height:31px;font-size:30px}main{padding-top:10px}.intro{margin-bottom:10px}.intro h1{font-size:23px}nav button{min-height:47px}.scene{height:calc(100vh - 388px);min-height:300px}.question{padding:10px 15px}.question .eyebrow{display:none}.question h2{margin:0}.controls,.readout{padding:10px 15px}.controls .section-title{display:none}.switch-row small{display:none}.slider-row{min-height:35px}.metrics strong{font-size:21px}.readout p{font-size:15px}.stage-caption{min-height:24px}.timeline{margin:9px 0 11px}}
@media(max-width:900px){header{padding:12px 14px}main{padding:14px 12px 7px}.intro h1{font-size:23px}.intro p{margin-top:7px;font-size:13px}.workspace{grid-template-columns:1fr}.scene{height:370px;min-height:350px}.scene-heading{top:68px;font-size:16px;left:17px}.scene-tools{left:12px;right:12px;top:11px;justify-content:flex-end}.scene-tools button{font-size:12px;min-height:40px;padding:7px}.outer{top:109px}.inner{bottom:59px}.compartment{font-size:14px}.compartment strong{font-size:17px}.legend{font-size:10px;gap:8px}.orbit-hint{display:none}nav{gap:5px}nav button{font-size:14px;padding:8px 2px;min-height:55px}nav button b{font-size:10px}.floating-label{font-size:12px}.playbar button{font-size:14px;padding:9px;min-height:44px}.primary{min-width:110px}.speed{font-size:12px;gap:4px}.speed select{min-height:40px;padding:4px}.stage-caption strong{font-size:15px}.transport-strip{padding:12px}.controls,.readout{padding:16px 18px}.slider-row{font-size:16px;min-height:42px}.switch-row{font-size:16px;min-height:47px}.presets button,.readout button{font-size:14px;min-height:44px}.question{padding:17px}.question h2{font-size:20px}.metrics strong{font-size:25px}.readout p{font-size:16px}.workspace:is(:fullscreen,.presentation){grid-template-columns:1fr;display:block;padding:8px;overflow:auto}.workspace:is(:fullscreen,.presentation) .scene{height:53vh}.workspace:is(:fullscreen,.presentation) aside{margin-top:10px}}
@media(max-width:370px){.speed{display:none}.playbar{justify-content:space-between}.playbar button{flex:1}.primary{min-width:0}.floating-label{font-size:11px}.scene-tools button{padding:6px}.legend{font-size:9px}}

.workspace.presentation{position:fixed;inset:0;z-index:1000;}

@media(max-width:600px){.floating-label{display:none}.scene-tag{display:inline-block;font-size:11px}}
.workspace:is(:fullscreen,.presentation){grid-template-rows:auto minmax(0,1fr)}
.workspace:is(:fullscreen,.presentation)>nav{grid-column:1/-1;margin:0;flex-shrink:0}
.workspace:is(:fullscreen,.presentation)>.lab{grid-column:1;grid-row:2}
.workspace:is(:fullscreen,.presentation)>aside{grid-column:2;grid-row:2}
@media(max-width:900px){.workspace:is(:fullscreen,.presentation)>nav{margin-bottom:8px}}

@media(max-width:370px){nav{grid-template-columns:repeat(3,1fr)}nav button{white-space:nowrap}.playbar .primary{flex:1.35;white-space:nowrap}}
.contrast-toggle{position:absolute;right:16px;bottom:54px;min-height:44px;padding:8px 14px;background:#173e4d;color:#edf8f3;border:1px solid #91b9c4;font-size:15px;font-weight:600;z-index:2}.contrast-toggle:hover{background:#2c5867}.contrast-toggle[aria-pressed=true]{background:#d0e5b4;color:#142b25;border-color:#e5f4d2}.scene.high-contrast{background:#050b10;color:#f4fff9}.high-contrast .floating-label{background:#060e16;color:#f4fff9;border-color:#bbd9dd;box-shadow:0 2px 8px #0009}.high-contrast .cargo-label{color:#ffe1ad;border-color:#f2c887}.high-contrast .compartment small,.high-contrast .orbit-hint,.high-contrast .legend{color:#d0e5eb}.high-contrast .scene-tag{color:#e0edf2;border-color:#91b3bd;background:#0c1c25}.high-contrast .scene-tools button{background:#122c38;color:#f4fff9;border-color:#8cabb5}.high-contrast .floating-label::after{background:#d0e5eb}.high-contrast .cargo-label::after{background:#ffe1ad}.high-contrast .live-dot{box-shadow:none}.high-contrast .tail{background:#68bcc9}@media(max-width:600px){.contrast-toggle{right:12px;bottom:50px;font-size:14px}}

@media(max-width:600px){.contrast-toggle{top:58px;bottom:auto;right:12px}.scene-heading{max-width:calc(100% - 130px)}}@media(max-width:370px){.scene-heading .scene-tag{display:none}}

.contrast-toggle{transition:none}.contrast-toggle[aria-pressed=true]:hover{background:#e0f2c3}
.lab{position:relative}.scene-tools{position:absolute;left:auto;right:12px;top:76px;width:100px;display:flex;flex-direction:column;gap:5px;z-index:3}.scene-tools button{font-size:14px;min-height:44px;padding:8px 5px;background:#183e4c;color:#edf8f5;border:1px solid #8babba;white-space:nowrap}.zoom-tools{display:grid;grid-template-columns:1fr 1fr;gap:5px}.zoom-tools button{font-size:23px;padding:2px}.scene-tools button[aria-pressed=true]{background:#d0e5b4;color:#17382e;border-color:#e1f2c8}.scene-tools button[aria-pressed=true]:hover{background:#e0f2c3}.scene-fullscreen{position:absolute;right:14px;top:14px;min-height:44px;background:#183e4c;color:#edf8f5;border-color:#8babba;font-size:14px;padding:8px 12px}.scene-fullscreen:hover{background:#2c5867}.high-contrast .scene-fullscreen{background:#122c38;color:#f4fff9;border-color:#aec8d0}.gesture-help{margin-top:8px;font-size:13px;line-height:1.65;color:#365d52}.gesture-help summary{cursor:pointer;min-height:28px;padding:3px 0;font-size:14px}.gesture-help p{margin:6px 0}.gesture-help>div{padding:6px 10px;border:1px solid #d5e1d8;border-radius:8px;background:#f2f7ef}.scene-heading{top:23px}.orbit-hint{right:16px}.scene-tools button:focus-visible,.scene-fullscreen:focus-visible{outline:3px solid #ffe094;outline-offset:2px}
@media(max-width:1200px) and (min-width:901px){.scene-heading{top:23px}.outer{top:95px}.scene-tools{right:10px;left:auto;top:73px;width:91px}}
@media(max-width:900px){.scene-tools{position:static;width:auto;display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:7px;padding:10px 12px 0;background:#fff}.zoom-tools{display:contents}.scene-tools #navigationMode{grid-column:span 2}.scene-tools #homeView,.scene-tools #frontView{grid-column:span 2}.scene-tools button{font-size:14px;min-height:44px;background:#f0f5ee;color:#234a3e;border-color:#c9d8ce}.zoom-tools button{font-size:22px}.scene-tools button[aria-pressed=true]{background:#234f44;color:#fff}.scene-heading{top:25px;max-width:calc(100% - 100px)}.scene-fullscreen{top:14px;right:12px}.contrast-toggle{top:65px;bottom:auto}.outer{top:120px}.gesture-help summary{min-height:38px;display:flex;align-items:center}.gesture-help summary:before{content:'▸';margin-right:7px}.gesture-help[open] summary:before{content:'▾'}.gesture-help p{font-size:14px}}

/* Keep contrast separate from the camera rail in short desktop viewports. */
@media(min-width:901px){.contrast-toggle{top:14px;bottom:auto;right:82px}}