✓ 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
All required features are implemented with correct physics (gold 19.3 g/cm³, alloy 13.0 g/cm³, same 1000 g mass), visually clear water-rise difference, working Heureka fade-in at slider end, and splash effects — but mass/volume/density panel values are static (not live-updating per submersion fraction), and the submerged-fraction calculation ignores the rising water surface feedback loop.
All required features are implemented with correct physics (gold 19.3 g/cm³, alloy 13.0 g/cm³, same 1000 g mass), visually clear water-rise difference, working Heureka fade-in at slider end, and splash effects — but mass/volume/density panel values are static (not live-updating per submersion fraction), and the submerged-fraction calculation ignores the rising water surface feedback loop.