:root{--bg: #1e1f22;--panel: #26282c;--raised: #31343a;--border: #3c4047;--text: #e9e9eb;--muted: #a3a7ad;--accent: #e2a458;--accent-text: #1e1f22;--danger: #e5675c;--canvas-bg: #7f7f7f;--plane-fg: #ff8a3d;--plane-mg: #4caf50;--plane-bg: #3d7bff;--plane-erase: #ffffff;--radius: 8px;--tap: 44px;color-scheme:dark}*{box-sizing:border-box}html,body{margin:0;height:100%;background:var(--bg);color:var(--text);font:15px/1.4 system-ui,-apple-system,Segoe UI,Roboto,sans-serif;-webkit-text-size-adjust:100%;overscroll-behavior:none}.app{position:fixed;inset:0;display:flex;flex-direction:column;padding:env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left)}button,.button{min-height:var(--tap);padding:0 14px;border:1px solid var(--border);border-radius:var(--radius);background:var(--raised);color:var(--text);font:inherit;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;gap:8px;-webkit-tap-highlight-color:transparent;user-select:none;-webkit-user-select:none}button:disabled{opacity:.45;cursor:default}button.active,.segmented button.active{background:var(--accent);border-color:var(--accent);color:var(--accent-text)}.button.primary{background:var(--accent);border-color:var(--accent);color:var(--accent-text);font-weight:600}.file-button input{display:none}button:focus-visible,.button:focus-within,input:focus-visible,select:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.topbar{display:flex;align-items:center;flex-wrap:wrap;gap:8px 12px;padding:8px 12px;border-bottom:1px solid var(--border);background:var(--panel)}.brand{font-weight:700;letter-spacing:.02em;margin-right:4px}.views{display:flex;gap:4px;flex-wrap:wrap}.actions{display:flex;gap:8px;margin-left:auto}.workspace{flex:1;display:flex;min-height:0}.canvas-area{flex:1;min-width:0;display:flex;flex-direction:column;position:relative}.stage-container{flex:1;position:relative;overflow:hidden;background:var(--canvas-bg);touch-action:none;user-select:none;-webkit-user-select:none;-webkit-touch-callout:none}.stage{position:absolute;left:0;top:0;transform-origin:0 0}.stage canvas{position:absolute;left:0;top:0;width:100%;height:100%;display:block}.caption{margin:0;padding:10px 14px;border-top:1px solid var(--border);background:var(--panel);color:var(--muted)}.empty{flex:1;display:flex;flex-direction:column;justify-content:center;padding:24px max(16px,8vw);background:var(--canvas-bg);color:#111}.empty h1{margin:0 0 12px;font-size:26px}.empty ol{margin:0;padding-left:22px;font-size:17px}.empty li{margin:6px 0}.busy,.error{position:absolute;left:50%;top:16px;transform:translate(-50%);padding:10px 16px;border-radius:var(--radius);background:#141416e0;color:var(--text);box-shadow:0 4px 16px #00000059;max-width:calc(100% - 32px)}.error{display:flex;align-items:center;gap:12px;border:1px solid var(--danger)}.panel{width:300px;flex-shrink:0;overflow-y:auto;-webkit-overflow-scrolling:touch;border-left:1px solid var(--border);background:var(--panel)}.panel-inner{padding:4px 14px 24px}.panel section{padding:12px 0;border-bottom:1px solid var(--border)}.panel section:last-child{border-bottom:0}.panel h2{margin:0 0 10px;font-size:12px;font-weight:600;text-transform:uppercase;letter-spacing:.08em;color:var(--muted)}.panel section>*+*{margin-top:10px}.tool-grid{display:grid;grid-template-columns:1fr 1fr;gap:6px}.tool{justify-content:flex-start;padding:0 10px}.focal-tool{width:100%}.ring{width:14px;height:14px;border-radius:50%;border:2px solid currentColor;box-shadow:0 0 0 2px #00000040;flex-shrink:0}.swatch{width:14px;height:14px;border-radius:50%;border:1px solid rgba(0,0,0,.4);flex-shrink:0}.segmented{display:flex}.segmented button{flex:1;border-radius:0}.segmented button:first-child{border-radius:var(--radius) 0 0 var(--radius)}.segmented button:last-child{border-radius:0 var(--radius) var(--radius) 0;border-left:0}.row{display:flex;gap:6px;flex-wrap:wrap}.row button{flex:1;padding:0 8px}.slider{display:block}.slider-label{display:flex;justify-content:space-between;color:var(--text)}.slider-label output{color:var(--muted);font-variant-numeric:tabular-nums}.slider input{width:100%;height:var(--tap);margin:0;accent-color:var(--accent)}.toggle{display:flex;align-items:center;gap:10px;min-height:36px}.toggle input{width:20px;height:20px;accent-color:var(--accent)}.select{display:flex;align-items:center;justify-content:space-between;gap:10px}.select select{min-height:var(--tap);padding:0 10px;border-radius:var(--radius);border:1px solid var(--border);background:var(--raised);color:var(--text);font:inherit}.hint{margin:0;color:var(--muted);font-size:13px}.status{margin:0;color:var(--muted);font-size:12px;font-variant-numeric:tabular-nums}@media(max-width:860px),(orientation:portrait)and (max-width:1100px){.workspace{flex-direction:column}.panel{width:auto;max-height:42%;border-left:0;border-top:1px solid var(--border)}.panel-inner{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));column-gap:20px}.panel section:last-child{border-bottom:1px solid var(--border)}.caption{font-size:13px}}.why-cards{display:grid;gap:8px}.why-card{background:var(--raised);border:1px solid var(--border);border-radius:var(--radius);padding:10px 12px}.why-card h3{margin:0 0 4px;font-size:14px;font-weight:600}.why-card p{margin:0;font-size:13px;line-height:1.45}.why-card .tip{margin-top:6px;color:var(--muted)}.row .button{flex:1;padding:0 8px}.compare-bar{display:flex;align-items:center;gap:10px;padding:4px 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6px;font-size:14px}.lesson-sheet h3{margin:0 0 2px;font-size:12px}.lesson-sheet p{margin:0 0 4px}.sheet-date{margin:0;color:#555}.sheet-figures{display:grid;grid-template-columns:1fr 1fr;gap:14px 18px;margin-top:14px}.sheet-figures.portrait{grid-template-columns:1fr 1fr 1fr}.lesson-sheet figure{margin:0;break-inside:avoid;page-break-inside:avoid}.lesson-sheet figure canvas{display:block;width:100%;height:auto;border:1px solid #ccc}.lesson-sheet figcaption{margin-top:4px}.lesson-sheet figure .value-scale{margin-top:6px}.sheet-block{margin-top:16px;break-inside:avoid;page-break-inside:avoid}.sheet-card{margin-bottom:8px;break-inside:avoid;page-break-inside:avoid}.sheet-settings{color:#555;border-top:1px solid #ccc;padding-top:6px}.lesson-sheet .value-step .share,.lesson-sheet .swatch-meta{color:#555}.lesson-sheet .swatch-meta strong{color:#1a1a1a}.lesson-sheet .swatches{grid-template-columns:repeat(8,1fr)}@media(max-width:600px){.lesson-sheet{padding:16px}.sheet-figures,.sheet-figures.portrait{grid-template-columns:1fr}.lesson-sheet .swatches{grid-template-columns:repeat(4,1fr)}}@media print{@page{margin:12mm}html,body{height:auto;overflow:visible;background:#fff}.app,.sheet-toolbar{display:none!important}.sheet-backdrop{position:static;overflow:visible;padding:0;background:none}.lesson-sheet{max-width:none;padding:0;border-radius:0}.sheet-figures{grid-template-columns:1fr 1fr}.sheet-figures.portrait{grid-template-columns:1fr 1fr 1fr}.lesson-sheet .swatches{grid-template-columns:repeat(8,1fr)}}