✓ 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
Exceptionally complete implementation hitting every required feature — physics values are correct (19.3 vs 4.5 g/cm³, same 1000 g mass), water rises proportionally, splash and Heureka animations fire on cue, and the info panel live-updates all four quantities; minor weakness is that submerged-fraction logic uses the static BASE_WATER_Y rather than the dynamically rising surface, so displacement slightly underestimates at full submersion.
Exceptionally complete implementation hitting every required feature — physics values are correct (19.3 vs 4.5 g/cm³, same 1000 g mass), water rises proportionally, splash and Heureka animations fire on cue, and the info panel live-updates all four quantities; minor weakness is that submerged-fraction logic uses the static BASE_WATER_Y rather than the dynamically rising surface, so displacement slightly underestimates at full submersion.