✓ 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 crowns to air correctly, but the HTML range input with orient=vertical has bottom=0/top=100 visually, making the thumb movement misleading); physics values are plausible (19.2 vs 10.0 g/cm³, same 1000g mass) but submerged fraction calculation uses arbitrary pixel estimates rather than true geometry, and water level rise formula is a rough approximation.
Slider direction is inverted (value=0 at top maps crowns to air correctly, but the HTML range input with orient=vertical has bottom=0/top=100 visually, making the thumb movement misleading); physics values are plausible (19.2 vs 10.0 g/cm³, same 1000g mass) but submerged fraction calculation uses arbitrary pixel estimates rather than true geometry, and water level rise formula is a rough approximation.