✓ 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 21 required features are implemented with correct physics (gold 19.3 g/cm³, gilded ~8.9 g/cm³, same 1000 g mass), smooth water-rise animation, splash/ripple particles, buoyancy force arrows, live panel stats, and a polished confetti Heureka overlay — minor weakness is that the water-rise is scaled aesthetically in pixels rather than a true volumetric representation, and the slider only triggers splash checks on downward movement.
All 21 required features are implemented with correct physics (gold 19.3 g/cm³, gilded ~8.9 g/cm³, same 1000 g mass), smooth water-rise animation, splash/ripple particles, buoyancy force arrows, live panel stats, and a polished confetti Heureka overlay — minor weakness is that the water-rise is scaled aesthetically in pixels rather than a true volumetric representation, and the slider only triggers splash checks on downward movement.