:root{--bg: #f4f5f7;--panel: #ffffff;--ink: #1b1d21;--ink-soft: #5b6068;--line: #d6d9de;--accent: #c0392b;--accent-soft: #e8a49b;--metal: #9aa3ad;--metal-dark: #6b7480;--metal-light: #c7ced6;--piston: #b8bec6;--rod: #7f8893;--crank: #5a626d;--bore: #2a2d33;--combustion: #e25822;--valve-intake: #3a7bd5;--valve-exhaust: #d9534f;--spark: #b58900;--spark-flash: #ffd34d;--stroke-intake: #3a7bd5;--stroke-compression: #e0a020;--stroke-power: #d1452f;--stroke-exhaust: #7a828c}@media(prefers-color-scheme:dark){:root{--bg: #15171c;--panel: #1e2127;--ink: #e7eaef;--ink-soft: #9aa1ac;--line: #2c313a;--accent: #e74c3c;--accent-soft: #7a2c25;--metal: #7e8794;--metal-dark: #4a525d;--metal-light: #aab2bd;--piston: #8f97a2;--rod: #6a727d;--crank: #444b55;--bore: #0d0f12;--combustion: #ff6a33;--valve-intake: #5b9bff;--valve-exhaust: #ff6b66;--spark: #ffd23f;--spark-flash: #fff6c2;--stroke-intake: #5b9bff;--stroke-compression: #f0bb3a;--stroke-power: #ff5e44;--stroke-exhaust: #9aa1ac}}*{box-sizing:border-box}html,body{margin:0;min-height:100%;background:var(--bg);color:var(--ink);font:15px/1.45 system-ui,-apple-system,Segoe UI,Roboto,sans-serif;-webkit-font-smoothing:antialiased}#app{display:grid;grid-template-columns:1fr 320px;grid-template-rows:auto 1fr;grid-template-areas:"header header" "stage  controls";height:100vh;height:100dvh}.app-header{grid-area:header;padding:12px 20px;border-bottom:1px solid var(--line);background:var(--panel);display:flex;align-items:baseline;flex-wrap:wrap;gap:8px 14px}#mode-switch{margin-left:auto;align-self:center;min-height:34px}.segmented{display:inline-flex;border:1px solid var(--line);border-radius:8px;overflow:hidden}.segmented button{border:0;background:var(--panel);color:var(--ink-soft);padding:6px 14px;font-size:13px;cursor:pointer}.segmented button+button{border-left:1px solid var(--line)}.segmented button:hover{color:var(--ink)}.segmented button.active{background:var(--accent);color:#fff}.segmented button.active:hover{color:#fff}.segmented.grow{display:flex;margin-bottom:14px}.segmented.grow button{flex:1;padding:8px 4px}.app-header h1{margin:0;font-size:20px;letter-spacing:.5px}.subtitle{margin:0;color:var(--ink-soft);font-size:13px}.stage{grid-area:stage;position:relative;overflow:hidden}#scene{display:block;width:100%;height:100%;touch-action:pan-y}#scene.orbit{cursor:grab;touch-action:none}#scene.orbit.orbiting{cursor:grabbing}.hint-pill{position:absolute;top:12px;left:50%;transform:translate(-50%);background:var(--panel);color:var(--ink-soft);border:1px solid var(--line);border-radius:999px;padding:6px 14px;font-size:13px;white-space:nowrap;pointer-events:none;box-shadow:0 2px 8px #0000001f}.parts-wrap{position:absolute;top:12px;left:12px}.parts-btn{width:auto;margin-bottom:0;padding:8px 14px;font-size:13px;background:var(--panel);box-shadow:0 2px 8px #0000001f}.parts-menu{position:absolute;top:calc(100% + 8px);left:0;width:210px;padding:10px 10px 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0%))}.control input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;width:20px;height:20px;margin-top:-7px;border:none;border-radius:50%;background:var(--accent);box-shadow:0 1px 3px #0000004d;cursor:pointer}.control input[type=range]::-moz-range-track{height:6px;border-radius:3px;background:linear-gradient(to right,var(--accent) var(--fill, 0%),var(--line) var(--fill, 0%))}.control input[type=range]::-moz-range-thumb{width:20px;height:20px;border:none;border-radius:50%;background:var(--accent);box-shadow:0 1px 3px #0000004d;cursor:pointer}.control input[type=range]:focus-visible{outline:2px solid var(--accent);outline-offset:2px;border-radius:4px}.control input[type=range]:disabled::-webkit-slider-thumb{background:var(--ink-soft);cursor:not-allowed}.control input[type=range]:disabled::-moz-range-thumb{background:var(--ink-soft);cursor:not-allowed}.btn{width:100%;padding:9px 12px;border:1px solid var(--line);border-radius:8px;background:var(--bg);color:var(--ink);font-size:14px;cursor:pointer}.btn:hover{border-color:var(--accent)}.btn.active{background:var(--accent);color:#fff;border-color:var(--accent)}.btn-primary{background:var(--accent);color:#fff;border-color:var(--accent);font-size:15px;font-weight:600;padding:12px}.btn-primary:hover{filter:brightness(1.08)}.btn-primary.running{background:var(--panel);color:var(--accent);font-weight:600}@keyframes start-pulse{0%,to{box-shadow:0 0 color-mix(in srgb,var(--accent) 45%,transparent)}70%{box-shadow:0 0 0 10px color-mix(in srgb,var(--accent) 0%,transparent)}}.btn-start.pulse{animation:start-pulse 1.8s ease-out infinite}@media(prefers-reduced-motion:reduce){.btn-start.pulse{animation:none}}.btn-row{display:flex;gap:8px;margin-bottom:14px}.btn-sm{padding:7px 6px;font-size:13px}.btn[type=button]{margin-bottom:14px}.control.is-disabled{opacity:.45}.control input[type=range]:disabled{cursor:not-allowed}.readout{display:grid;grid-template-columns:1fr auto;gap:4px 10px;padding:12px;margin:8px 0 14px;border:1px solid var(--line);border-radius:8px;font-size:13px}.readout .k{color:var(--ink-soft)}.readout .v{text-align:right;font-variant-numeric:tabular-nums;font-weight:600}.section-title{font-size:11px;text-transform:uppercase;letter-spacing:.8px;color:var(--ink-soft);margin:4px 0 10px}.caption{font-size:12px;color:var(--ink-soft);margin:2px 0 6px}.panel-section{border-top:1px solid var(--line)}.section-head{width:100%;display:flex;align-items:center;gap:8px;padding:12px 0;border:0;background:none;color:var(--ink-soft);font-size:11px;font-weight:600;text-transform:uppercase;letter-spacing:.8px;cursor:pointer;text-align:left}.section-head:hover{color:var(--ink)}.section-head .chev{font-size:10px;transition:transform .15s ease}.panel-section.open>.section-head .chev{transform:rotate(90deg)}.section-body{display:none;padding-bottom:12px}.panel-section.open>.section-body{display:block}.panel-section.sub{border-top:1px dashed var(--line);margin-top:2px}.panel-section.sub>.section-head{padding:10px 0;font-weight:500}.hidden{display:none!important}.about{max-width:760px;margin:0 auto;padding:40px 20px 60px;color:var(--ink)}.about h2{font-size:20px;margin:28px 0 8px}.about p,.about li{color:var(--ink-soft);font-size:15px}.about a{color:var(--accent)}.about footer{margin-top:36px;padding-top:16px;border-top:1px solid var(--line);font-size:13px;color:var(--ink-soft)}@media(pointer:coarse){.btn{min-height:44px}.segmented button{min-height:42px;padding:10px 14px}.section-head{padding:14px 0}.control input[type=range]{height:40px}.control input[type=range]::-webkit-slider-thumb{width:24px;height:24px;margin-top:-9px}.control input[type=range]::-moz-range-thumb{width:24px;height:24px}}.diagram-canvas{display:none}@media(max-width:720px){#app{display:block;height:auto}.app-header{position:sticky;top:0;z-index:5;padding:8px 12px;gap:2px 10px;align-items:center}.app-header h1{font-size:17px}.subtitle{order:3;flex-basis:100%;font-size:12px}#mode-switch{order:2}.stage{height:calc(100dvh - 505px);min-height:220px}.diagram-canvas{display:block;width:100%;height:130px;border-bottom:1px solid var(--line);cursor:pointer;touch-action:pan-y}.controls{border-left:none;border-top:none;height:auto;overflow:visible;min-height:884px;padding:10px 14px calc(14px + env(safe-area-inset-bottom))}.cockpit .control{margin-bottom:10px}.cockpit .caption{margin-bottom:0}}@media(max-width:460px){.subtitle{display:none}}