✓ 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
ASCII-art canvas renders both crowns and rising water level with correct physics values (gold 19.32 g/cm³, gilded 12.0 g/cm³, same 100 g mass), but the slider is direction-inverted (transform:rotate(180deg) visually flips it yet the value mapping remains top=0=air which is correct by accident but UX feels backwards), splash effects are faked as static '~' chars rather than real particles, and both crowns move identically so there's no visual differentiation of differing volumes in the scene.
ASCII-art canvas renders both crowns and rising water level with correct physics values (gold 19.32 g/cm³, gilded 12.0 g/cm³, same 100 g mass), but the slider is direction-inverted (transform:rotate(180deg) visually flips it yet the value mapping remains top=0=air which is correct by accident but UX feels backwards), splash effects are faked as static '~' chars rather than real particles, and both crowns move identically so there's no visual differentiation of differing volumes in the scene.