✓ 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 with correct physics (ρ_gold=19.3, ρ_fake=5.5, same 1000g mass), live panel covering all four values, ripple/splash FX, sparkle-heureka overlay, and a volume comparison bar — slight weakness is that water-rise pixel scale (0.5 px/cm³) is arbitrary and the visual rise is very subtle for the gold crown at full submersion.
Exceptionally complete implementation with correct physics (ρ_gold=19.3, ρ_fake=5.5, same 1000g mass), live panel covering all four values, ripple/splash FX, sparkle-heureka overlay, and a volume comparison bar — slight weakness is that water-rise pixel scale (0.5 px/cm³) is arbitrary and the visual rise is very subtle for the gold crown at full submersion.