✓ 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
Near-complete implementation with correct physics (gold 19.3 g/cm³, gilded 11.2 g/cm³, same 1000 g mass), animated falling/submerging crowns, rising water levels, splash effects, sparkle Heureka overlay, and live side-panel + SVG data readouts — minor flaw is the slider has no visible top/bottom label orientation cues and the crown position mapping uses somewhat arbitrary pixel scales rather than strict proportional geometry.
Near-complete implementation with correct physics (gold 19.3 g/cm³, gilded 11.2 g/cm³, same 1000 g mass), animated falling/submerging crowns, rising water levels, splash effects, sparkle Heureka overlay, and live side-panel + SVG data readouts — minor flaw is the slider has no visible top/bottom label orientation cues and the crown position mapping uses somewhat arbitrary pixel scales rather than strict proportional geometry.