:root{color-scheme:light;--ink:#203345;--muted:#7a8996;--border:#e4eaf0;--green:#159c79;--blue:#4285cf;--orange:#d89532;--purple:#9272cf;--red:#e06470}
[hidden]{display:none!important}
.element-choice{margin:0 25px 22px;display:flex;align-items:center;justify-content:space-between;font-size:13px;gap:16px}
.element-choice select{min-width:170px;border:1px solid #dbe5e9;border-radius:7px;padding:9px 12px;color:var(--ink);background:#f8fbfa;font:inherit;cursor:pointer}
.learning{margin-top:20px;scroll-margin-top:20px}
.learning-header{border-bottom:1px solid #edf1f4}
.mode-switch{display:flex;align-items:center;gap:8px;font-size:12px;white-space:nowrap;cursor:pointer;color:#547e6d}
.mode-switch input{accent-color:var(--green);width:17px;height:17px;cursor:pointer}
.learning-intro{padding:0 24px;font-size:12px;line-height:1.9;color:#82929f}
.learning-toolbar{display:flex;align-items:center;flex-wrap:wrap;gap:9px;padding:8px 24px 12px;background:#fbfdfc}
.learning-toolbar button{border:1px solid #dce6e1;background:white;border-radius:6px;padding:8px 12px;color:#4f6d60;font:inherit;font-size:12px;cursor:pointer}
.learning-toolbar button:hover:not(:disabled){background:#ecf7f1}
.learning-toolbar button:disabled,.locate-button:disabled{opacity:.45;cursor:default}
#learning-progress{font-size:12px;color:#779185;margin:0 4px;font-variant-numeric:tabular-nums}
.learning-state{font-size:11px;color:#739587;padding:0 24px;line-height:1.8;min-height:20px}
.learning-steps{display:grid;grid-template-columns:1fr 1fr;gap:16px;padding:0 24px 20px}
.learning-steps.is-updating{opacity:.45;pointer-events:none}
.learning-step{min-width:0;border:1px solid #e4ebee;border-radius:10px;padding:19px 20px;background:#fcfdfd;overflow-wrap:anywhere}
.learning-step h3{font-size:14px;font-weight:600;display:flex;gap:10px;align-items:center;margin:0 0 13px}
.step-number{color:#549c83;font-size:11px;font-variant-numeric:tabular-nums;background:#eaf4ef;border-radius:4px;padding:4px 5px}
.learning-step p{font-size:12px;line-height:1.95;color:#657c8a;margin:9px 0}
.math-formula{font-size:15px;margin:12px 0;padding:9px 10px;overflow-x:auto;overflow-y:hidden;background:#f3f7f8;border-radius:6px;max-width:100%}
.math-formula .katex-display{margin:4px 0;text-align:left}
.math-formula .katex-display>.katex{text-align:left}
.formula-fallback{font-size:13px;line-height:1.9;white-space:normal;overflow-wrap:anywhere}
.locate-button{background:white;color:#41846f;border:1px solid #d5e6dc;border-radius:5px;padding:6px 9px;font:inherit;font-size:11px;margin:8px 7px 0 0;cursor:pointer}
.locate-button:hover:not(:disabled){background:#ebf5ef;border-color:#a5cdb9}
.learning-conclusion{margin:0 24px 24px;padding:16px 20px;background:#eef7f2;border:1px solid #dfebe4;border-radius:9px;font-size:12px;line-height:1.9;color:#46785e}
.learning-conclusion strong{font-size:13px}.learning-conclusion p{margin:7px 0}.learning-conclusion small{color:#7b9686;font-size:10px}
.ray-table-wrap{max-width:100%;overflow-x:auto;margin:12px 0}
.ray-table-wrap table{width:100%;border-collapse:collapse;font-size:11px;color:#607987;white-space:nowrap}
.ray-table-wrap th,.ray-table-wrap td{border-bottom:1px solid #e2e9ed;text-align:left;padding:8px 10px;font-weight:400}
.ray-table-wrap th{color:#426b61;background:#eff5f2}
@media(max-width:850px){.learning-steps{grid-template-columns:1fr}.learning-step{padding:17px}.learning-header{flex-wrap:wrap}.learning-toolbar{padding-left:18px;padding-right:18px}}
@media(max-width:480px){.learning-steps{padding:0 14px 15px;gap:12px}.learning-intro,.learning-state{padding:0 16px}.learning-conclusion{margin:0 14px 16px}.learning-header h2{font-size:14px}.mode-switch{font-size:11px}.math-formula{font-size:13px}}
.rotation-controls{border-top:1px solid var(--border);padding-top:20px!important}.angle-entry{display:flex;gap:9px;align-items:center;margin-top:15px;font-size:12px;color:#71818e}.angle-entry input{width:76px;padding:7px 8px;border:1px solid #dbe5e9;border-radius:6px;font:inherit;color:var(--ink);background:#fbfdfc}.angle-entry button{margin-left:auto;border:1px solid #acd5c5;background:#f0f8f4;border-radius:6px;padding:8px 12px;font:inherit;color:#298568;cursor:pointer}.control-hint{font-size:11px;color:#8a99a3;line-height:1.8;margin:10px 0 0}.line.local-axis{color:var(--green)}.line.extension{color:var(--orange)}.rotation-results{margin:0 25px 17px;font-size:11px;color:#7b8d99;line-height:1.8}.rotation-results p{margin:7px 0;overflow-wrap:anywhere}.model-warning{padding:10px 12px;background:#f1f6f8;border-radius:7px}.model-warning.limited{background:#fff6e8;color:#9c702a}.rotation-handle{cursor:grab;touch-action:none;outline:none}.rotation-handle:active{cursor:grabbing}.rotation-handle:focus-visible circle{stroke:#228569;stroke-width:3}#diagram{touch-action:pan-y;user-select:none}.metrics .metric>div{font-size:clamp(19px,2.6vw,29px)}#property-tags{flex-wrap:wrap}
*{box-sizing:border-box}body{margin:0;background:#f4f7fa;color:var(--ink);font-family:"Segoe UI","Microsoft YaHei",sans-serif;-webkit-font-smoothing:antialiased}.laboratory{max-width:1320px;margin:auto;padding:42px 40px 24px}.page-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:28px}.eyebrow{font-size:12px;letter-spacing:1px;color:#6f8394}.brand-icon{font-size:23px;color:var(--green);vertical-align:middle;margin-right:8px}.divider{padding:0 12px;color:#bec9d2}h1{font-size:30px;font-weight:650;margin:15px 0 8px;letter-spacing:-.7px}h1 span{font-size:15px;font-weight:400;letter-spacing:0;margin-left:21px;color:#7b8b98}.intro{font-size:13px;color:var(--muted);margin:0}.live-badge{display:flex;align-items:center;gap:8px;font-size:12px;color:#44816e;background:#e7f3ed;border:1px solid #d8ebe2;padding:8px 12px;border-radius:30px}.live-badge i{width:6px;height:6px;border-radius:50%;background:#25a47b}.panel{background:#fff;border:1px solid var(--border);border-radius:15px;box-shadow:0 4px 20px #20334503;overflow:hidden}.panel-header{padding:21px 24px;display:flex;justify-content:space-between;align-items:center;gap:10px}.panel-header>div{display:flex;align-items:center;gap:10px}.section-index{font-size:10px;font-weight:600;color:#8297a5;background:#f0f4f7;border-radius:5px;padding:5px 6px}h2{font-size:15px;font-weight:600;margin:0}.unit-label{font-size:11px;color:#8b99a5}#diagram-container{width:100%;height:410px;background:#fcfdfe;border-top:1px solid #f0f3f6;border-bottom:1px solid #f0f3f6}#diagram{width:100%;height:100%;display:block}#diagram text{font-family:"Segoe UI","Microsoft YaHei",sans-serif}.legend{display:flex;justify-content:center;gap:24px;flex-wrap:wrap;padding:18px 20px 8px;font-size:11px;color:#71818e}.legend>span{display:flex;align-items:center;gap:7px}.swatch{height:9px;width:9px;border-radius:3px}.object{background:var(--green)}.image{background:var(--red)}.line{width:21px;border-top:2px solid}.parallel{color:var(--blue)}.focal{color:var(--orange)}.central{color:var(--purple)}.dashed{color:#8e9daa;border-top-style:dashed}.view-note{text-align:center;min-height:18px;font-size:11px;color:#8b97a2;margin:6px 18px 15px;line-height:1.7}.workspace{display:grid;grid-template-columns:1.12fr 1fr;gap:20px;margin-top:20px}.slider-group{padding:0 25px;margin:5px 0 23px}.slider-heading{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px;font-size:13px}.slider-heading em,.metric em{font-family:Georgia,serif;margin-left:5px}output{font-size:23px;font-weight:600;color:var(--green);font-variant-numeric:tabular-nums}output small{font-size:11px;font-weight:400;color:#8c9aa5}input[type=range]{appearance:none;-webkit-appearance:none;width:100%;height:5px;margin:8px 0;background:linear-gradient(to right,var(--green) 0%,var(--green) var(--fill),#e7edf1 var(--fill),#e7edf1 100%);border-radius:5px;cursor:pointer;touch-action:pan-y}input[type=range]::-webkit-slider-thumb{appearance:none;width:17px;height:17px;background:#fff;border:4px solid var(--green);border-radius:50%;box-shadow:0 1px 5px #159c7933}input[type=range]::-moz-range-thumb{width:10px;height:10px;background:#fff;border:4px solid var(--green);border-radius:50%}input:focus-visible,button:focus-visible{outline:3px solid #94d7c6;outline-offset:5px}.range-labels{display:flex;justify-content:space-between;font-size:10px;color:#99a5af;margin-top:5px}.preset-label{font-size:11px;color:#8999a5;margin:0 25px 10px}.presets{display:flex;gap:8px;margin:0 25px 24px}.presets button{flex:1;background:#f8fafb;border:1px solid #e5ebef;border-radius:8px;color:#516777;font:inherit;font-size:11px;padding:11px 6px;cursor:pointer;line-height:1.6;transition:background .15s,border-color .15s}.presets button span{display:block;font-size:10px;color:#94a2ac;margin-top:3px}.presets button:hover,.presets button[aria-pressed=true]{background:#edf8f3;border-color:#a9d8c7;color:#22876b}.metrics{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:5px 25px 20px}.metric{padding:16px 20px;background:#f6f9fb;border:1px solid #edf1f4;border-radius:9px}.metric>span{font-size:12px;color:#7d8e9c}.metric>div{font-size:29px;font-weight:600;margin-top:8px;font-variant-numeric:tabular-nums}.metric small{font-size:12px;font-weight:400;color:#8c9aa5;margin-left:6px}.image-property{margin:0 25px}.property-caption{font-size:11px;color:#8b99a4}#property-tags{display:flex;gap:7px;margin-top:10px}.tag{font-size:11px;padding:5px 10px;border-radius:5px;background:#eaf5f0;color:#42856c}.tag:nth-child(2){background:#eef1fa;color:#6e80ad}.tag:nth-child(3){background:#faf2e7;color:#a6834c}#result-description{font-size:12px;color:#82929f;line-height:1.8;min-height:22px}.formula{margin:17px 25px 23px;padding-top:17px;border-top:1px solid #edf1f4;display:flex;justify-content:space-between;align-items:center;gap:12px;font-size:10px;color:#94a0aa;flex-wrap:wrap}.formula strong{font-family:Georgia,serif;font-size:15px;font-weight:400;color:#627789}.formula b{font-weight:400;color:#627789;margin-left:6px}footer{font-size:11px;text-align:center;color:#97a3ad;line-height:1.8;margin:21px 0 0}
@media(min-width:1500px){.laboratory{padding-top:55px}#diagram-container{height:460px}}@media(max-width:850px){.laboratory{padding:25px 20px}.workspace{grid-template-columns:1fr}h1 span{display:block;margin:10px 0 0}.legend{gap:12px 20px}#diagram-container{height:360px}.live-badge{white-space:nowrap}.page-header{gap:12px}.panel-header{padding:18px 20px}}@media(max-width:480px){.laboratory{padding:20px 12px}.live-badge{display:none}h1{font-size:26px}.unit-label{font-size:9px}.legend{font-size:10px}#diagram-container{height:320px}.presets{margin-left:18px;margin-right:18px}.metrics{margin-left:18px;margin-right:18px}.metric{padding:15px}.metric>div{font-size:25px}}