:root{--bg:#080d18;--text:#edf0f7;--dim:#a3afc5;--gold:#ffd185;--blue:#80cdf1;--line:#283348;--pink:#ff99ae}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text);font:18px/1.5 system-ui,-apple-system,sans-serif}button,input{font:inherit}button{cursor:pointer;border:1px solid #48576c;background:#111d2e;color:var(--text);border-radius:7px;padding:10px 16px;min-height:44px}button:hover,button[aria-pressed=true]{background:#273a50;border-color:var(--gold)}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid var(--gold);outline-offset:4px}button:disabled{opacity:.3;cursor:default}a{color:var(--blue)}[hidden]{display:none!important}.toolbar{height:68px;padding:0 4vw;display:flex;align-items:center;gap:32px;border-bottom:1px solid var(--line)}.brand{font-size:14px;font-weight:800;letter-spacing:.16em;text-decoration:none;color:var(--gold)}#chapter{font-size:14px;color:var(--dim)}.tools{display:flex;gap:8px;margin-left:auto}.tools 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span{font-weight:700;font-size:23px}.legend p{font-size:18px}.data-row{display:flex;justify-content:space-between;align-items:center;gap:16px;padding:12px 0;border-bottom:1px solid var(--line);font-size:17px}.data-row strong{color:var(--blue);white-space:nowrap;font-weight:500}.source{display:block;font-size:12px;margin-top:20px}figcaption{font-size:11px;color:var(--dim);margin-top:9px}.crop{position:relative;width:100%;aspect-ratio:5/4;overflow:hidden;background:#000}.crop img{position:absolute;width:480%;max-width:none;left:-286%;top:-224%}.crop svg{position:absolute;width:100%;height:100%;max-height:none}.crop 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button{display:block;width:100%;text-align:left;border:0;font-size:14px}#speakerNotes{position:fixed;z-index:20;bottom:88px;left:0;right:0;background:#182538f5;border-top:1px solid var(--gold);padding:20px 5vw;font-size:16px;max-height:40vh;overflow:auto}#speakerNotes p{margin:8px 0 0;color:#c7d1df}#scene3d{padding:0;background:#030712;border-radius:10px;overflow:hidden}#lens3d{display:block;width:100%;height:min(39vh,420px);touch-action:none;cursor:grab}.mass-ctl{padding:0 18px 8px}.mass-ctl label{font-size:13px;margin-top:2px}.scene-fs{position:absolute;top:8px;right:8px;min-height:32px;padding:5px 9px;font-size:11px}#scene3d:fullscreen{display:flex;flex-direction:column;justify-content:center}#scene3d:fullscreen canvas{height:80vh!important}
@media(min-width:1000px) and (max-height:760px){.slide{gap:12px;padding-top:20px;padding-bottom:20px}.eyebrow{margin-bottom:7px}h2{font-size:34px}.slide-head p{font-size:19px}.hint{font-size:15px}.result{margin:14px 0}.formula{margin-bottom:18px}.data-row{padding:9px 0}.small{margin-top:10px}}
@media(max-width:800px){body{font-size:16px}.toolbar{height:60px;padding:0 18px;gap:12px}#chapter{display:none}.brand{font-size:11px}.tools{gap:5px}.tools button{font-size:11px;padding:6px 8px}#fullscreenBtn{display:none}main{height:calc(100dvh - 140px);min-height:0}.slide{padding:23px 22px;gap:16px}.split,.split.wide{grid-template-columns:1fr;gap:12px;flex:initial}.cover{display:flex;flex-direction:column;align-items:stretch;gap:18px}.cover h1{font-size:43px}.cover .lede{font-size:19px}.cover .hero{flex-shrink:0;height:260px}.cover .eyebrow{font-size:10px}h2{font-size:29px}.slide-head p{font-size:17px}.visual svg{max-height:30vh}.explain{padding-bottom:6px}.formula{font-size:24px;margin-bottom:10px}label{margin-top:10px}.result{font-size:25px;margin:12px 0}.hint{font-size:15px;margin-top:12px}.small{font-size:12px}.presets{margin:10px 0}.presets button{font-size:12px;padding:8px 11px}.photo-zoom{max-width:380px;width:100%;margin:auto}.crop{aspect-ratio:5/4}.crop svg{max-height:none}.equation-key{flex-direction:column;gap:8px;margin-top:15px}.algebra>p{font-size:19px}.algebra .huge{font-size:29px;min-height:130px}.calc-inputs{max-width:none}.calc-inputs label{font-size:14px}.calc-inputs input{padding:6px 10px}.data-row{font-size:15px}.navigation{height:80px;padding:10px 16px;gap:12px}.navigation button{padding:8px 12px}.navigation button span{display:none}.key-hint{display:none}#overview{right:12px;width:min(340px,calc(100% - 24px))}#speakerNotes{bottom:80px;font-size:14px}#lens3d{height:30vh;min-height:230px}.mass-ctl label{font-size:12px}.cluster{max-height:30vh}.reveal{font-size:16px}.photo-marker{top:62%}.copy .lede{margin-bottom:18px}}
@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}@media print{.toolbar,.navigation,#overview,#speakerNotes{display:none!important}main{height:auto}.slide,.slide[hidden]{display:flex!important;height:180mm;break-after:page;overflow:hidden}.cover{display:grid!important}.split{grid-template-columns:1fr 1fr}.slide input,.slide button{display:none}body{print-color-adjust:exact}}
@media(min-width:801px){.photo-zoom{width:min(100%,calc(125dvh - 445px));margin-inline:auto}}
/* Real observations under the live model overlays. */
.photo-backed>svg{background:#030712;border-radius:8px}.photo-backed .hubble-photo{opacity:1}.photo-backed .model-overlays>.galaxy{opacity:0}.photo-backed.diagram-mode .hubble-photo{opacity:0}.photo-backed.diagram-mode .model-overlays>.galaxy{opacity:1}.photo-backed.overlays-hidden .model-overlays{visibility:hidden}.photo-backed svg text{paint-order:stroke;stroke:#080d18;stroke-width:4px;stroke-linejoin:round}.photo-controls{display:flex;justify-content:center;gap:8px;margin-top:10px}.photo-controls button{font-size:12px;padding:6px 10px;min-height:36px}.photo-credit{font-size:11px;line-height:1.4;color:var(--dim);text-align:center;margin:8px 0 0}.photo-backed>svg{max-height:36vh}.scene-observation{margin:0 0 16px;display:grid;grid-template-columns:130px 1fr;align-items:center;gap:12px}.scene-observation svg{width:130px;height:115px;background:#030712;border-radius:6px}.scene-observation figcaption{font-size:11px}.split.wide .legend p{font-size:16px;margin-bottom:10px}.split.wide .legend span{font-size:19px}.photo-zoom .photo-controls{margin-top:6px}.photo-zoom .photo-controls button{min-height:32px}.photo-backed #halo{mix-blend-mode:screen}@media(min-width:801px){.measure-photo{width:min(100%,calc(125dvh - 505px))}}@media(max-width:800px){.photo-backed>svg{max-height:32vh}.scene-observation{grid-template-columns:110px 1fr;margin-bottom:10px}.scene-observation svg{width:110px;height:100px}.photo-credit{font-size:10px}.photo-controls{margin-top:7px}}