✓ Two crowns ✓ Same mass, different density ✓ Vertical slider ✓ Slider works ✓ Slider controls crowns — Slider direction correct ✓ Full slider range — Fall animation ✓ Water displacement ✓ Rising water level ✓ Splash effects — Physics correct — Live mass value ✓ Live volume value ✓ Live density value ✓ Live displaced water — Gilded displaces more ✓ Heureka animation ✓ No external deps ✓ Light bg / dark text ✓ Self-contained HTML
Slider direction is inverted (0%=air is at bottom, 100%=water is at top for a vertical range), live displays show averaged values rather than per-crown values making the key comparison invisible, and the "fall animation" is an instant CSS translate with no easing — the core Archimedes teaching moment (gilded crown visually displacing more) is never clearly demonstrated.
Slider direction is inverted (0%=air is at bottom, 100%=water is at top for a vertical range), live displays show averaged values rather than per-crown values making the key comparison invisible, and the "fall animation" is an instant CSS translate with no easing — the core Archimedes teaching moment (gilded crown visually displacing more) is never clearly demonstrated.