✓ 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
Slider direction is inverted (value=0 at top maps to crowns in air, but HTML range inputs with vertical orientation render 0 at bottom on most browsers, making top=water); physics scaling is toy-sized (19.3 g mass at gold density gives 1 ml volume, which is a grape, not a crown) and the submerged-depth interpolation is geometrically ad-hoc rather than truly Archimedean, but relative behavior (gilded displaces more) is qualitatively correct.
Slider direction is inverted (value=0 at top maps to crowns in air, but HTML range inputs with vertical orientation render 0 at bottom on most browsers, making top=water); physics scaling is toy-sized (19.3 g mass at gold density gives 1 ml volume, which is a grape, not a crown) and the submerged-depth interpolation is geometrically ad-hoc rather than truly Archimedean, but relative behavior (gilded displaces more) is qualitatively correct.