:root{font-family:PingFang SC,Microsoft YaHei,sans-serif;color:#272e28;background:#fafbf8;font-synthesis:none;font-weight:400;--green: #285b40;--line: #e6e8e1}*{box-sizing:border-box}body{margin:0}button,a,input,select{-webkit-tap-highlight-color:transparent}button,input,select{font:inherit}button{cursor:pointer;border:0;background:none;color:inherit}button:disabled{opacity:.45;cursor:default}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible{outline:2px solid #659875;outline-offset:4px}a{color:inherit;text-decoration:none}header{height:94px;background:#fff;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);padding:0 36px;gap:25px}.brand{display:flex;align-items:center;gap:12px;color:var(--green)}.brand b{font-size:23px;letter-spacing:3px}.brand small{display:block;font-size:8px;letter-spacing:2.3px;margin-top:4px}.brand span{display:block}nav{display:flex;align-self:stretch;gap:35px}nav button{position:relative;font-size:15px;color:#777f76;padding:0 6px}nav button span{font-size:9px;margin-right:7px;color:#a0a59e}nav button.active{color:var(--green);font-weight:600}nav button.active:after{content:"";position:absolute;bottom:0;left:0;right:0;height:3px;background:var(--green)}.guide-button{display:flex;align-items:center;gap:9px;font-size:13px}main{display:grid;grid-template-columns:minmax(0,1fr) 326px;min-height:calc(100svh - 94px)}.workspace{min-width:0;display:flex;flex-direction:column}.scene-area{position:relative;min-height:570px;flex:1;background:#f3f1eb;isolation:isolate}.canvas-host{position:absolute;inset:0}.canvas-host canvas{display:block;touch-action:none}.intro{position:absolute;top:32px;left:38px;pointer-events:none}.eyebrow{font-size:10px;letter-spacing:1.4px;color:#7a8275;display:flex;align-items:center;gap:10px}.eyebrow span{width:18px;height:1px;background:#9ea695}h1{font-size:31px;letter-spacing:1px;font-weight:500;margin:13px 0 11px}.intro p{font-size:12px;color:#7a8175;margin:0;letter-spacing:.4px}.scene-corner{position:absolute;top:35px;right:30px;font-size:10px;color:#838b7d;display:flex;gap:7px;align-items:center}.live-dot{width:5px;height:5px;border-radius:50%;background:#518763}.view-home{position:absolute;right:25px;bottom:145px;width:33px;height:33px;display:grid;place-items:center;background:#ffffffa1;border:1px solid #dcded4;border-radius:50%}.scene-note{position:absolute;left:38px;bottom:138px;color:#989e91;font-size:10px;display:flex;align-items:center;gap:7px}.observation{position:absolute;left:38px;bottom:109px;font-size:11px;color:#747e6d;max-width:80%;line-height:1.5}.toolbar{position:absolute;bottom:35px;left:38px;right:30px;display:flex;justify-content:space-between;align-items:center;gap:12px}.modes{display:flex;gap:3px;padding:5px;background:#ffffffce;border:1px solid #dfe2d7;border-radius:7px;box-shadow:0 5px 15px #4f5b3810}.modes button{padding:9px 15px;font-size:12px;border-radius:4px;color:#858b80}.modes .selected{color:var(--green);background:#e9efe4;font-weight:500}.transport{display:flex;align-items:center;gap:10px;background:#ffffffb0;border:1px solid #dfe2d7;padding:5px 8px;border-radius:7px}.transport button{display:grid;place-items:center;width:30px;height:30px}.transport .play{background:var(--green);color:#fff;border-radius:4px}.transport select{background:transparent;border:0;font-size:12px;width:65px;color:#687361}.readings{display:flex;align-items:center;gap:25px;min-height:156px;padding:25px 35px;background:#fff;border-top:1px solid var(--line)}.metric{min-width:90px;flex:1}.metric>span{font-size:11px;color:#8d9488;display:block;margin-bottom:10px}.metric>div{display:flex;align-items:baseline;gap:7px;white-space:nowrap}.metric strong{font-size:30px;font-weight:400;letter-spacing:-1px;font-variant-numeric:tabular-nums}.metric small{font-size:10px;color:#8f9885}.chart{width:30%;min-width:170px;border-left:1px solid var(--line);padding-left:25px}.chart-title{display:flex;justify-content:space-between;color:#909785;font-size:9px}.chart-title span{display:flex;align-items:center;gap:5px}.chart-title i{width:4px;height:4px;background:var(--green);border-radius:50%}.chart svg{width:100%;height:85px;display:block}.chart svg text{font:9px sans-serif;fill:#a2a799}footer{display:flex;justify-content:space-between;align-items:center;padding:15px 35px;font-size:9px;color:#969d8e;background:#fafbf8}footer button{display:flex;align-items:center;gap:6px;font-size:9px}aside{background:#fff;border-left:1px solid var(--line);padding:34px 27px 25px}.panel-title{display:flex;align-items:center;justify-content:space-between}.panel-title h2{font-size:21px;font-weight:500;margin:0}.panel-title>span{font-size:9px;color:#9ca393;letter-spacing:1.5px}.muted{font-size:11px;color:#91988b;margin:12px 0 28px}.range-field{display:block;margin-bottom:22px}.range-field>span{display:flex;align-items:center;justify-content:space-between;font-size:12px}.range-field output{font-size:14px;font-variant-numeric:tabular-nums;color:#3e5338}.range-field output small{margin-left:6px;font-size:10px;color:#8a947e}.range-field input{display:block;width:100%;margin:16px 0 9px;appearance:none;height:3px;background:#dce3d5;border-radius:3px;cursor:pointer;accent-color:var(--green)}.range-field input::-webkit-slider-thumb{appearance:none;width:12px;height:12px;background:var(--green);border-radius:50%;box-shadow:0 0 0 3px #fff}.range-limits{color:#acb2a5}.range-limits small{font-size:9px}.reverse{display:flex;align-items:center;justify-content:center;gap:10px;width:100%;border:1px solid #ddd7c9;padding:10px;font-size:12px;color:#936a50;border-radius:4px;margin-top:5px}.reverse[aria-pressed=true]{background:#fcf0e8}.switch-row{display:flex;align-items:center;justify-content:space-between;margin:22px 0;font-size:12px;cursor:pointer}.switch-row small{display:block;color:#a6ad9f;font-size:9px;margin-top:6px}.switch-row input{appearance:none;width:29px;height:17px;border-radius:20px;background:#c5ccbf;cursor:pointer;position:relative}.switch-row input:checked{background:var(--green)}.switch-row input:after{content:"";position:absolute;top:3px;left:3px;width:11px;height:11px;border-radius:50%;background:#fff;transition:transform .2s}.switch-row input:checked:after{transform:translate(12px)}.power{margin-top:-7px}.lesson{border-top:1px solid var(--line);padding-top:26px;margin-top:25px}.lesson-label{display:flex;align-items:center;justify-content:space-between;font-size:13px}.lesson-label small{font-size:8px;color:#a4ac9a}.lesson h3{font-size:13px;font-weight:500;line-height:1.9;margin:17px 0}.lesson fieldset{margin:0;padding:0;border:0;display:grid;gap:8px}.answer{display:flex;align-items:center;gap:10px;border:1px solid #e5e9df;border-radius:4px;padding:10px 11px;font-size:11px;cursor:pointer;min-height:39px}.answer input{position:absolute;opacity:0;width:1px;height:1px}.answer:has(input:focus-visible){outline:2px solid #659875}.answer-letter{font-size:10px;color:#9ea790}.answer.chosen{border-color:#77946c;background:#f3f7ee}.answer svg{margin-left:auto;color:var(--green)}.primary{background:var(--green);color:#fff;padding:12px 14px;border-radius:4px;display:flex;justify-content:space-between;align-items:center;width:100%;margin-top:15px;font-size:12px}.task-note{font-size:9px;color:#a1aa97;margin:11px 0 0}.principle{border-top:1px solid var(--line);margin-top:28px;padding-top:20px}.principle>span{font-size:10px;color:#929d86}.principle>div{font-family:Georgia,serif;font-size:24px;color:#435a38;margin:15px 0;font-style:italic}.principle p{font-size:10px;line-height:1.9;color:#919b86;margin-bottom:0}.result{background:#f0f5eb;padding:13px;margin-top:15px;border-radius:4px;color:#48603a}.result>b{font-size:12px}.result p{font-size:11px;line-height:1.9}.result button{font-size:10px;display:flex;align-items:center;gap:6px;padding:0;color:var(--green)}.loading{position:absolute;inset:155px 0 170px;display:flex;align-items:center;justify-content:center;gap:12px;color:#7b886e;font-size:12px;background:#f3f1eb}.loading button{border-bottom:1px solid}.spin{animation:spin 4s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.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}dialog{max-width:620px;width:calc(100% - 36px);border:1px solid #dce3d5;border-radius:12px;padding:30px;color:#343f2f;box-shadow:0 30px 100px #23371c30}dialog::backdrop{background:#27372470;-webkit-backdrop-filter:blur(5px);backdrop-filter:blur(5px)}.dialog-heading{display:flex;align-items:center;justify-content:space-between;font-size:12px;color:#7e8e70}dialog h2{font-size:27px;font-weight:500;margin:28px 0 15px}dialog h3{font-size:14px;margin-top:25px}dialog p{font-size:12px;line-height:2;color:#7d8a72}dialog>a{display:flex;align-items:center;gap:8px;font-size:12px;color:var(--green);margin:18px 0}.guide-index{border-top:1px solid var(--line);margin-top:20px}.guide-index button{width:100%;display:flex;gap:15px;align-items:center;padding:15px 0;border-bottom:1px solid var(--line)}.guide-index span{font-size:10px;color:#8f9c83}.guide-index b{font-size:12px;font-weight:500}.guide-index svg{margin-left:auto}dialog>small{display:block;font-size:9px;line-height:1.8;color:#99a38f;margin-top:20px}@media(min-width:1450px){main{grid-template-columns:minmax(0,1fr) 365px}aside{padding:38px 35px}.scene-area{min-height:650px}h1{font-size:37px}.intro{top:38px;left:48px}.intro p{font-size:13px}.toolbar{left:48px;right:40px}.readings{padding:28px 45px;gap:36px}.metric strong{font-size:36px}.chart{width:31%}}@media(max-width:1100px){header{padding:0 23px}nav{gap:15px}main{grid-template-columns:minmax(0,1fr) 290px}aside{padding:28px 20px}.scene-corner{display:none}.intro{left:25px}h1{font-size:27px}.readings{padding:20px;gap:16px;flex-wrap:wrap}.chart{width:100%;padding:10px 0 0;border-left:0;border-top:1px solid var(--line)}.chart svg{height:65px}.toolbar{left:22px;right:22px}.modes button{padding:9px 10px}.observation,.scene-note{left:25px}.transport{gap:3px}footer{padding:15px 20px}}@media(max-width:760px){header{height:122px;padding:18px 20px 0;flex-wrap:wrap;gap:8px}.brand b{font-size:20px}.brand svg{width:32px}.brand small{font-size:7px;letter-spacing:1.8px}.guide-button{margin-left:auto;font-size:11px}.guide-button svg{width:15px}nav{width:100%;order:3;height:43px;gap:0;justify-content:space-between}nav button{font-size:13px;padding:0 10px}main{display:block}.scene-area{height:560px;min-height:0}.intro{top:26px;left:23px}h1{font-size:27px;margin-top:11px}.intro p{font-size:10px;max-width:310px;line-height:1.8}.eyebrow{font-size:9px}.toolbar{bottom:23px;left:18px;right:18px;flex-wrap:wrap;gap:9px}.modes{padding:4px}.modes button{font-size:11px;padding:9px 10px}.transport{padding:4px;gap:2px}.transport select{width:54px;font-size:11px}.transport button{width:25px;height:28px}.observation{bottom:95px;left:23px;font-size:9px;max-width:85%}.scene-note{bottom:130px;font-size:9px;left:23px}.view-home{bottom:125px;right:19px}.readings{gap:12px;padding:23px}.metric{min-width:80px}.metric strong{font-size:26px}.metric>div{gap:4px}.metric small{font-size:9px}.metric>span{font-size:10px}.chart{margin-top:10px}.chart svg{height:80px}.chart-title{font-size:10px}footer{font-size:8px}footer button{font-size:8px}aside{border-left:0;border-top:1px solid var(--line);padding:30px 25px}.range-field{margin-bottom:25px}.range-field>span{font-size:13px}.range-field input{margin-top:22px}.lesson-label,.lesson h3{font-size:14px}.answer{font-size:12px;padding:13px}.primary{font-size:13px}.principle p{font-size:12px}.principle>span{font-size:12px}.result p{font-size:12px}}@media(prefers-reduced-motion:reduce){.spin{animation:none}*{scroll-behavior:auto}}@media(min-width:761px){main{height:calc(100svh - 94px);min-height:620px}aside{overflow-y:auto;scrollbar-width:thin;scrollbar-color:#d5ddcf transparent}.scene-area{min-height:0}.readings{min-height:125px;padding-top:15px;padding-bottom:15px}footer{flex-shrink:0}.intro{top:27px}h1{margin-top:10px}.toolbar{bottom:20px}.scene-note{bottom:104px}.observation{bottom:80px}.view-home{bottom:93px}}@media(min-width:761px)and (max-width:1100px){.readings{min-height:175px}.chart{display:none}}.canvas-host{inset:105px 0 83px}@media(max-width:760px){.canvas-host{inset:115px 0 132px}}@media(max-width:760px){.scene-area{flex:none;height:560px}.workspace{display:block}.canvas-host{inset:115px 0 132px}}.part-inspector{background:#f3f6ed;padding:13px;margin:0 0 24px;border-radius:5px}.part-inspector>div{display:flex;gap:7px}.part-inspector button{font-size:10px;padding:5px;color:#8a987b}.part-inspector button[aria-pressed=true]{color:var(--green);border-bottom:1px solid}.part-inspector p{font-size:11px;line-height:1.9;color:#77896a;margin-bottom:0}@font-face{font-family:Physics Sans;src:url(/fonts/physics-cn.woff2) format("woff2");font-weight:100 900;font-display:swap}:root{font-family:Physics Sans,PingFang SC,Microsoft YaHei,sans-serif}.chart{position:relative}.chart-note{position:absolute;top:35px;left:30px;font-size:9px;color:#829077;background:#ffffffdf;padding:6px}@media(min-width:1450px){main{grid-template-columns:minmax(0,1fr) 405px}nav{gap:55px}nav button{font-size:18px}.guide-button{font-size:15px}.range-field>span,.switch-row{font-size:15px}.range-field output{font-size:17px}.range-field output small,.range-limits small{font-size:11px}.range-field{margin-bottom:29px}.range-field input{margin-top:20px}.muted{font-size:13px}.panel-title h2{font-size:25px}.lesson-label{font-size:16px}.lesson h3{font-size:15px}.answer{font-size:14px;padding:13px}.answer-letter{font-size:12px}.primary,.reverse{font-size:14px;padding:13px}.principle p{font-size:12px}.principle>span{font-size:12px}.modes button{font-size:14px;padding:10px 17px}.metric>span{font-size:13px}.metric small{font-size:12px}.chart-title{font-size:11px}.scene-note,.observation{font-size:12px}.intro p{font-size:15px}}.engine-panel{border-bottom:1px solid var(--line);margin-bottom:24px;padding-bottom:20px}.engine-section-title{display:flex;align-items:center;justify-content:space-between;font-size:12px}.engine-section-title small{font-size:9px;color:#98a28f}.stroke-tabs{display:grid;grid-template-columns:repeat(4,1fr);gap:5px;margin:16px 0}.stroke-tabs button{border:1px solid #e1e5dc;border-radius:4px;padding:10px 0;font-size:12px;line-height:1.3}.stroke-tabs small{display:block;font-size:8px;color:#9ca491;letter-spacing:1px;margin-bottom:6px}.stroke-tabs button[aria-pressed=true]{border-color:var(--stroke);color:var(--stroke);background:color-mix(in srgb,var(--stroke) 8%,white)}.stroke-description{border-left:2px solid var(--stroke);padding-left:12px;min-height:75px;margin:18px 0}.stroke-description b{font-size:12px;font-weight:500;color:var(--stroke)}.stroke-description b small{font-size:9px;font-weight:400;letter-spacing:.5px;margin-left:10px}.stroke-description p{font-size:11px;line-height:1.9;color:#87917e;margin:8px 0}.angle-field{margin-top:22px;margin-bottom:15px}.engine-actions{display:flex;gap:9px}.engine-actions button{border:1px solid #dfe5d7;border-radius:4px;display:flex;justify-content:center;align-items:center;gap:8px;padding:9px;flex:1;font-size:10px;color:#6c7f5a}.valve-readout{display:flex;justify-content:space-between;font-size:10px;color:#969f8c;margin-top:17px}.valve-readout i{display:inline-block;width:5px;height:5px;background:#c5ccbf;border-radius:50%;margin-right:6px}.valve-readout i.open{background:#589779}.separation-field{margin:24px 0 0}.engine-parts{border-top:1px solid var(--line);padding-top:22px;margin-top:22px}.part-grid{display:grid;grid-template-columns:1fr 1fr;gap:6px;margin:15px 0}.part-grid button{text-align:left;border:1px solid #e4e8de;border-radius:4px;padding:9px;font-size:10px;color:#87937c}.part-grid button[aria-pressed=true]{background:#f0f4e9;border-color:#789266;color:#42622f}.part-description{background:#f4f6ee;border-radius:4px;padding:13px}.part-description>b{font-size:12px;font-weight:500;color:#5b7049}.part-description p{font-size:11px;line-height:1.9;color:#88947b;margin:8px 0 0}nav{min-width:0;overflow-x:auto;scrollbar-width:none}nav button{white-space:nowrap;flex-shrink:0}.brand,.guide-button{flex-shrink:0}dialog{max-height:90svh;overflow:auto}@media(min-width:1450px){nav{gap:32px}.engine-section-title,.stroke-tabs button,.stroke-description b{font-size:14px}.stroke-description p,.part-description p,.engine-actions button,.part-grid button{font-size:12px}.valve-readout{font-size:11px}}@media(max-width:760px){nav{gap:10px;justify-content:flex-start}.engine-section-title,.stroke-tabs button{font-size:14px}.stroke-description p,.part-description p,.part-grid button,.engine-actions button{font-size:12px}.angle-field input,.separation-field input{margin-top:24px}}.answer,.lesson fieldset{position:relative}.view-fullscreen{position:absolute;right:25px;bottom:134px;width:33px;height:33px;display:grid;place-items:center;background:#ffffffa1;border:1px solid #dcded4;border-radius:50%}.view-home svg{transform:scale(.9)}.engine-fullscreen-stages{display:none}.scene-area.immersive{position:fixed;inset:0;z-index:100;height:100svh;min-height:100svh;width:100vw;background:#f3f1eb}.scene-area.immersive .canvas-host{inset:95px 0 90px}.scene-area.immersive .engine-fullscreen-stages{display:block;position:absolute;left:38px;top:145px}.engine-fullscreen-stages button{padding:10px;border:1px solid #dce4d5;font-size:12px;background:#ffffffb0;margin-right:5px;border-radius:4px}.engine-fullscreen-stages button[aria-pressed=true]{background:#285b40;color:#fff}.engine-fullscreen-stages p{font-size:11px;color:#899780}@media(min-width:761px){main{overflow:hidden}}@media(max-width:760px){.view-fullscreen{right:19px;bottom:166px}.scene-area.immersive .engine-fullscreen-stages{top:125px;left:23px}.scene-area.immersive .canvas-host{inset:175px 0 125px}}.engine-selected-part{position:absolute;right:30px;top:95px;width:230px;max-width:calc(100vw - 46px);background:#ffffffe8;border:1px solid #dce4d5;padding:12px 15px;border-radius:6px;font-size:12px;line-height:1.8;color:#4e6554}.engine-selected-part summary{cursor:pointer}.engine-selected-part p{margin:8px 0 0}@media(max-width:760px){.engine-selected-part{right:auto;left:23px;top:205px;padding:6px 10px;width:auto}.engine-selected-part[open]{width:280px;z-index:2}.scene-area.immersive .canvas-host{inset:245px 0 125px}}