:root{color-scheme:dark;--bg:#080e19;--surface:#0c1524;--line:#223249;--text:#e9f0fa;--muted:#96a8c2;--blue:#62baff;--teal:#4de0bd;--gold:#ffcb72;--red:#ff758c}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text);font:16px/1.5 "Segoe UI","Microsoft YaHei",sans-serif}button,input,select{font:inherit}button,a,input,select{touch-action:manipulation}button{cursor:pointer;border:1px solid var(--line);border-radius:7px;padding:8px 12px;background:#111d2e;color:var(--text);transition:background .15s,border-color .15s}button:hover{background:#1a2c43;border-color:#4e6a8e}button:focus-visible,a:focus-visible,summary:focus-visible{outline:2px solid var(--blue);outline-offset:3px}button:disabled{cursor:default;opacity:.35}button.selected,button[aria-pressed=true]{background:#153654;border-color:#4f9ac9;color:#a8deff}.primary{background:#60b9f5;color:#071325;border-color:#60b9f5;font-weight:600}.primary:hover{background:#9bd9ff}a{color:inherit;text-decoration:none}.header{height:78px;display:flex;align-items:center;gap:30px;border-bottom:1px solid var(--line);padding:0 28px}.brand{display:flex;gap:12px;align-items:center}.brand svg{width:34px;fill:none;stroke:var(--blue);stroke-width:1.4}.brand span{font-size:21px;font-weight:600;letter-spacing:2px}.brand small{display:block;font-size:10px;letter-spacing:3px;color:var(--muted);font-weight:400}.course{color:#cad5e6;font-size:14px;flex:1}.course span{color:var(--muted);margin-left:14px}.header-button{font-size:14px}.workspace{display:grid;grid-template-columns:210px minmax(400px,1fr) 310px;min-height:calc(100dvh - 78px)}.navigation{padding:28px 16px 24px;border-right:1px solid var(--line);display:flex;flex-direction:column}.nav-heading{font-size:14px;color:var(--muted);display:flex;justify-content:space-between;margin:0 8px 24px}.nav-heading span{font-size:10px;letter-spacing:1px;align-self:center}.nav-group{margin-bottom:24px}.group-title{font-size:16px;display:flex;gap:10px;margin:0 8px 10px;align-items:baseline}.group-title em{font-style:normal;font-size:11px;color:var(--muted);letter-spacing:1.1px}.nav-item{width:100%;text-align:left;background:none;border:1px solid transparent;margin:3px 0;padding:10px 11px;color:#a0b0c8;display:flex;align-items:center;gap:12px;font-size:15px}.nav-item .num{font:12px "Segoe UI",sans-serif;color:#6c819e}.nav-item.active{background:#132c43;color:#caebff;border-color:#294c69}.nav-item.active .num{color:var(--blue)}.nav-foot{margin-top:auto;font-size:13px;line-height:1.8;color:#b2c2d8;padding:18px 8px 0}.nav-foot span{color:#7389a8;font-size:12px}.stage-panel{min-width:0;padding:27px 28px 22px;display:flex;flex-direction:column}.stage-header{display:flex;align-items:flex-start;justify-content:space-between;margin-bottom:15px}.eyebrow{font-size:11px;letter-spacing:1.6px;color:var(--blue)}h1{font-size:25px;font-weight:500;margin:5px 0}#sceneSubtitle{margin:0;font-size:14px;color:var(--muted)}.live-mark{display:flex;align-items:center;gap:7px;color:#9aadc8;font-size:12px;margin-top:8px}.live-mark span{width:6px;height:6px;background:var(--blue);border-radius:50%}#viewport{position:relative;flex:1;min-height:380px;height:calc(100dvh - 360px);max-height:760px;overflow:hidden;border:1px solid #233952;border-radius:12px;background:radial-gradient(ellipse at 50% 40%,#152b43 0,#0a1627 65%,#0a1220 100%)}#viewport canvas{display:block;width:100%;height:100%;touch-action:none;cursor:grab}#viewport canvas:active{cursor:grabbing}.stage-tools{position:absolute;right:15px;top:15px;z-index:4;display:flex;gap:4px;padding:4px;background:#0a1426d9;border:1px solid #26374d;border-radius:8px}.stage-tools button{font-size:13px;padding:5px 9px;background:transparent;border-color:transparent}.stage-tools button.selected{background:#1b3e59;color:#a3d9ff}.scene-result{position:absolute;bottom:44px;left:20px;z-index:4;font-size:14px;color:var(--gold);pointer-events:none;background:#091426bb;border-left:2px solid var(--gold);padding:6px 12px;max-width:calc(100% - 40px)}.axis-note{position:absolute;bottom:14px;left:20px;font-size:11px;color:#7088a7;pointer-events:none}.orbit-hint{position:absolute;bottom:14px;right:18px;font-size:11px;color:#839bbb;pointer-events:none}#loading{position:absolute;inset:0;display:grid;place-content:center;color:var(--muted);background:#0c1726;z-index:5}.stage-bottom{display:flex;align-items:center;gap:8px;padding:13px 0}.stage-bottom button{font-size:12px;padding:6px 9px;background:transparent;white-space:nowrap}.legend{flex:1;display:flex;gap:14px;flex-wrap:wrap;font-size:12px;color:#a7b8cf}.legend span{display:flex;gap:6px;align-items:center}.legend i{width:15px;height:2px;border-radius:1px;background:var(--c)}.stepper{border-top:1px solid var(--line);padding-top:16px;display:grid;grid-template-columns:1fr auto;gap:12px}.step-label{display:flex;align-items:center;gap:15px;font-size:13px;grid-column:1/-1}.step-label>span{color:var(--muted)}.step-label strong{font-weight:500}.step-label #stepCount{margin-left:auto;font:12px "Segoe UI",sans-serif;letter-spacing:1px}.step-buttons{display:flex;gap:7px;align-items:center}.step-buttons button{border-radius:4px;width:38px;height:28px;padding:0;font-size:12px;color:#7c91af}.step-buttons button.active{background:#264760;color:#c6e7fa;border-color:#5ba4d1}.step-buttons button.done{color:var(--blue)}.step-actions{display:flex;gap:7px}.step-actions button{font-size:13px;padding:6px 12px}.inspector{border-left:1px solid var(--line);background:#0c1422;padding:28px 22px;min-width:0}.section-heading{display:flex;align-items:center;justify-content:space-between;margin-bottom:20px}.section-heading h2{font-size:16px;margin:0;font-weight:500}.section-heading>span{font-size:10px;letter-spacing:1px;color:#608bb1}.field{font-size:14px;color:var(--muted);display:block}.field select{width:100%;margin-top:8px;background:#101f32;border:1px solid #2c405a;border-radius:6px;color:var(--text);padding:9px 10px;font-size:14px}.parameter{margin-top:22px}.parameter>div{display:flex;justify-content:space-between;font-size:14px;color:#acbbcf}.parameter output{color:var(--blue);font-variant-numeric:tabular-nums}.parameter input{width:100%;margin:13px 0 0;accent-color:var(--blue);cursor:pointer}.toggles{display:grid;grid-template-columns:1fr 1fr;gap:13px 5px;margin-top:23px}.toggles label{font-size:13px;display:flex;align-items:center;gap:6px;color:#b8c8db}.toggles input{accent-color:var(--blue);margin:0;width:15px;height:15px}.method-section{border-top:1px solid var(--line);margin-top:28px;padding-top:25px}.idea{font-size:15px;line-height:1.8;color:#c2d0e2;min-height:50px}.formula{padding:18px 5px;margin:14px 0;background:#122238;border:1px solid #254463;border-radius:8px;overflow:auto;font-size:16px}.katex-display{margin:0!important}.numeric{font-size:14px;line-height:1.7;color:var(--gold);font-variant-numeric:tabular-nums}details{margin-top:18px;color:#a9bbd2;font-size:13px}summary{cursor:pointer;margin-bottom:12px}.equations{font-size:13px;overflow:auto;line-height:2}.equations .katex-display{margin:10px 0!important}.note{margin-top:20px;padding-left:12px;border-left:2px solid #4f6a8a;font-size:13px;line-height:1.8;color:#9aadc5}.inspector-foot{font-size:11px;color:#6f83a0;margin-top:28px;line-height:1.9}#labels{position:absolute;inset:0;pointer-events:none;z-index:3}.model-label{position:absolute;color:var(--c);font-size:17px;font-family:Georgia,"Times New Roman",serif;font-style:italic;white-space:nowrap;text-shadow:0 1px 4px #040b18,0 0 8px #040b18;font-weight:600;line-height:1.25}#leaders{position:absolute;inset:0;pointer-events:none;z-index:2;width:100%;height:100%}#toast{position:fixed;left:50%;bottom:25px;transform:translateX(-50%);z-index:10;background:#203b54;border:1px solid #547b9c;padding:9px 18px;border-radius:7px;font-size:14px;opacity:0;pointer-events:none;transition:opacity .2s}#toast.show{opacity:1}body.present .navigation,body.present .inspector{display:none}body.present .workspace{grid-template-columns:1fr}body.present .stage-panel{max-width:1550px;width:100%;margin:auto}body.present #viewport{max-height:none;height:calc(100dvh - 326px)}body.present .stage-header h1{font-size:28px}body.present .scene-result{font-size:18px}body.present .model-label{font-size:21px}body.present .stage-header{margin-bottom:12px}body.present .step-label{font-size:16px}body.present .legend{font-size:14px}@media(min-width:1600px){.workspace{grid-template-columns:235px minmax(400px,1fr) 350px}.stage-panel{padding:32px 36px}.inspector{padding:32px 28px}.formula{font-size:19px}h1{font-size:28px}.navigation{padding:32px 20px}.nav-item{font-size:16px;padding:13px}.stage-bottom button{font-size:14px}}@media(max-width:1150px){.workspace{grid-template-columns:175px minmax(300px,1fr) 270px}.header{padding:0 18px}.stage-panel{padding:22px 18px}.inspector{padding:23px 16px}.navigation{padding:23px 10px}.nav-heading span{display:none}.nav-item{font-size:14px}.group-title em{font-size:9px}.stage-bottom{flex-wrap:wrap}.legend{flex-basis:100%}.formula{font-size:14px}.toggles{grid-template-columns:1fr}.orbit-hint{max-width:60%;font-size:10px}.step-actions button{padding:6px 8px}h1{font-size:22px}.course span{display:none}}@media(max-width:850px){.workspace{grid-template-columns:165px minmax(280px,1fr)}.inspector{grid-column:1/-1;border-left:0;border-top:1px solid var(--line);display:grid;grid-template-columns:1fr 1fr;gap:28px;padding:22px}.method-section{border-top:0;border-left:1px solid var(--line);margin:0;padding:0 0 0 22px}.inspector-foot{grid-column:1/-1;margin-top:0}.toggles{grid-template-columns:1fr 1fr}#viewport{height:450px;min-height:380px}.navigation{padding:24px 10px}.nav-foot{display:none}.stage-panel{padding:22px 16px}.stepper{grid-template-columns:1fr}.step-label{gap:8px}.step-actions{justify-content:flex-end}.brand small{display:none}.header{height:64px}.brand span{font-size:18px}.course{font-size:12px}.header{gap:20px}}@media(max-width:600px){.header{gap:10px;padding:0 12px}.brand span{font-size:17px}.brand svg{width:28px}.course{display:none}.header-button{margin-left:auto;font-size:12px}.workspace{display:flex;flex-direction:column}.navigation{padding:12px 12px 0;border-right:0;border-bottom:1px solid var(--line)}.nav-heading{display:none}#categoryNav{display:grid;grid-template-columns:1fr 1fr 1fr;gap:10px}.nav-group{margin-bottom:12px}.group-title{font-size:14px;margin:0 3px 7px}.group-title em{display:none}.nav-item{font-size:12px;padding:6px 7px;gap:5px;margin:1px 0}.nav-item .num{display:none}.stage-panel{padding:20px 12px}#viewport{min-height:340px;height:420px}.stage-header h1{font-size:22px}.stage-header p{font-size:12px}.stage-tools{right:8px;top:8px}.scene-result{font-size:13px;left:12px;bottom:39px}.axis-note{left:12px;font-size:10px}.orbit-hint{right:12px;font-size:10px}.inspector{display:block;padding:24px}.method-section{padding:25px 0 0;margin-top:25px;border-left:0;border-top:1px solid var(--line)}.formula{font-size:19px}.model-label{font-size:16px}.inspector-foot{margin-top:25px}body.present #viewport{height:calc(100dvh - 320px);min-height:350px}.stage-bottom{gap:7px}.stage-bottom button{font-size:12px}.legend{gap:12px}.step-label{flex-wrap:wrap}#stepName{font-size:14px}.step-label #stepCount{margin-left:auto}}
:is([hidden]){display:none!important}
:is(.group-title){flex-wrap:wrap;gap:3px 8px}.group-title>span{white-space:nowrap}.group-title em{font-size:10px}
.offline-link{font-size:13px;color:var(--muted);padding:8px 0}.offline-link:hover{color:var(--blue)}
.present-scene{display:none;max-width:240px;padding:8px 12px;border:1px solid #354f6c;border-radius:7px;background:#13263b;color:var(--text);font-size:14px}body.present .present-scene{display:block}body.present .course{flex:1}@media(max-width:600px){body.present .brand span{display:none}.present-scene{max-width:165px;font-size:12px}body.present .header{gap:8px}body.present .offline-link{display:none}}
.spatial-hint{margin:15px 0 0;color:#8098b7;font-size:12px;line-height:1.8}
/* Keep the model in view while each teaching sidebar scrolls independently. */
@media(min-width:701px){
 html,body{height:100%;overflow:hidden}
 body{height:100dvh;display:flex;flex-direction:column}
 .header{height:64px;flex:0 0 64px}
 .workspace{flex:1;min-height:0;overflow:hidden;grid-template-columns:190px minmax(0,1fr) 290px}
 .navigation,.inspector{min-height:0;height:100%;overflow-y:auto;overscroll-behavior:contain;scrollbar-gutter:stable;scrollbar-width:thin;scrollbar-color:#3b5776 #0c1524}
 .navigation{padding:20px 12px}
 .inspector{display:block;grid-column:auto;padding:20px 18px;border-left:1px solid var(--line);border-top:0}
 .nav-foot{display:block}
 .stage-panel{height:100%;min-height:0;overflow:hidden;padding:16px 20px 14px}
 .stage-header{flex:0 0 auto;margin-bottom:10px}
 #viewport,body.present #viewport{flex:1 1 0;height:auto;min-height:0;max-height:none}
 .stage-bottom{flex:0 0 auto;padding:10px 0;flex-wrap:wrap}
 .stepper{flex:0 0 auto;padding-top:10px;gap:8px;grid-template-columns:1fr auto}
 .method-section{border-left:0;border-top:1px solid var(--line);margin-top:24px;padding:20px 0 0}
 .inspector-foot{margin-top:24px}
 body.present .stage-panel{max-width:none;margin:0;padding:14px 24px}
 body.present .stage-header h1{font-size:25px}
}
@media(min-width:701px) and (max-width:1150px){
 .workspace{grid-template-columns:155px minmax(0,1fr) 250px}
 .stage-panel{padding:14px 12px 12px}
 .inspector{padding:18px 14px}
 .stage-bottom button{padding:5px 7px}
 .stage-header h1{font-size:21px}
 .stage-header p{font-size:12px}
 .legend{flex-basis:100%;gap:10px}
 .nav-heading{margin:0 5px 18px}
}
@media(min-width:1600px){.workspace{grid-template-columns:220px minmax(0,1fr) 330px}.stage-panel{padding:20px 26px}.inspector{padding:24px}}
@media(min-width:701px) and (max-height:650px){
 .header{height:52px;flex-basis:52px}
 .stage-panel{padding-top:10px;padding-bottom:10px}
 .stage-header .eyebrow{display:none}
 .stage-header h1{margin:0 0 3px;font-size:21px}
 .stage-bottom{padding:6px 0}
 .stepper{padding-top:7px;gap:5px}
}
.stage-header .stage-tools{position:static;flex:0 0 auto;align-self:flex-start;margin-top:4px;z-index:auto}
.scene-caption{flex:0 0 auto;border-top:1px solid var(--line);padding:7px 0 9px;font-size:12px;line-height:1.65;max-height:94px;overflow-y:auto;scrollbar-width:thin}
.scene-caption .scene-result,body.present .scene-caption .scene-result{position:static;background:none;border:0;padding:0;max-width:none;font-size:13px;color:var(--gold)}
#annotationKey{color:#a4b7d1}.scene-help{font-size:11px;color:#728aa9;margin-top:2px}
.stepper{padding-top:10px}
@media(max-width:1150px){.stage-header{gap:8px;flex-wrap:wrap}.stage-header .stage-tools{padding:2px;margin:0}.stage-tools button{padding:4px 7px;font-size:12px}.scene-caption{max-height:88px;font-size:11px}}
@media(min-width:701px){.stage-header h1{margin:3px 0}.stage-header #sceneSubtitle{max-width:100%;font-size:13px}.stage-bottom{padding:7px 0}.stage-header{margin-bottom:9px}.stage-header .eyebrow{font-size:10px}}
/* Presentation fills the available screen width, with minimal side gutters. */
body.present .workspace{width:100%;max-width:none}
body.present .stage-panel{width:100%;max-width:none;margin:0;padding-left:8px;padding-right:8px}
body.present #viewport{width:100%;max-width:none;border-radius:8px}
/* Give the initial and fullscreen views more vertical room for geometry. */
@media(min-width:701px){
 body:not(.present) .stage-panel{padding-top:10px;padding-bottom:8px}
 body:not(.present) .stage-header{margin-bottom:6px;gap:8px;flex-wrap:nowrap}
 body:not(.present) .stage-header>div:first-child{min-width:0}
 body:not(.present) .stage-header .eyebrow{display:none}
 body:not(.present) .stage-header h1{font-size:22px;margin:0 0 2px}
 body:not(.present) #sceneSubtitle{font-size:12px;line-height:1.5}
 body:not(.present) .stage-tools{gap:1px;padding:2px;margin:0}
 body:not(.present) .stage-tools button{padding:4px 6px;font-size:12px}
 body:not(.present) .stage-bottom{padding:5px 0;gap:5px}
 body:not(.present) .stage-bottom button{padding:4px 6px;font-size:12px}
 body:not(.present) .legend{font-size:11px;gap:8px}
 body:not(.present) .scene-caption{padding:4px 0 6px;font-size:11px;line-height:1.5;max-height:70px}
 body:not(.present) .scene-help{display:none}
 body:not(.present) .stepper{grid-template-columns:minmax(0,1fr) auto auto;gap:8px;align-items:center;padding-top:7px}
 body:not(.present) .step-label{grid-column:auto;gap:7px;font-size:12px;flex-wrap:wrap}
 body:not(.present) .step-label>span:first-child{display:none}
 body:not(.present) .step-label #stepCount{margin-left:0;font-size:10px}
 body:not(.present) .step-actions button{padding:5px 7px;font-size:12px}
}
.stage-panel:fullscreen{width:100vw;height:100dvh;max-width:none;margin:0;padding:10px 12px;background:var(--bg);display:flex;flex-direction:column}
.stage-panel:fullscreen #viewport{flex:1 1 0;min-height:0;max-height:none;height:auto}
/* Presentation also prioritizes canvas height while keeping controls visible. */
@media(min-width:701px){
 body.present .stage-panel{padding-top:8px;padding-bottom:8px}
 body.present .stage-header{margin-bottom:6px;gap:8px;flex-wrap:nowrap}
 body.present .stage-header>div:first-child{min-width:0}
 body.present .stage-header .eyebrow{display:none}
 body.present .stage-header h1{font-size:24px;margin:0 0 2px}
 body.present #sceneSubtitle{font-size:12px;line-height:1.5}
 body.present .stage-tools{margin:0;padding:2px}
 body.present .stage-bottom{padding:5px 0;gap:7px;flex-wrap:nowrap}
 body.present .legend{font-size:12px;flex-basis:auto;gap:12px}
 body.present .stage-bottom button{padding:4px 7px;font-size:12px}
 body.present .scene-caption{padding:4px 0 6px;font-size:12px;line-height:1.5;max-height:66px}
 body.present .scene-help{display:none}
 body.present .stepper{grid-template-columns:minmax(0,1fr) auto auto;gap:12px;align-items:center;padding-top:7px}
 body.present .step-label{grid-column:auto;gap:10px;font-size:14px;flex-wrap:wrap}
 body.present .step-label>span:first-child{display:none}
 body.present .step-label #stepCount{margin-left:0;font-size:11px}
 body.present .step-actions button{padding:5px 10px;font-size:13px}
}