✓ 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 (min=0 at top → crowns in air is correct numerically but the vertical-lr/rtl CSS makes the physical top of the slider correspond to value 100/water, not air); physics values are plausible and the gilded crown clearly displaces more, but the water-rise label shows raw pixels rather than cm³, and mass/volume/density cards are static (not truly "live" per-frame).
Slider direction is inverted (min=0 at top → crowns in air is correct numerically but the vertical-lr/rtl CSS makes the physical top of the slider correspond to value 100/water, not air); physics values are plausible and the gilded crown clearly displaces more, but the water-rise label shows raw pixels rather than cm³, and mass/volume/density cards are static (not truly "live" per-frame).