✓ 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 is top/crowns in air which is correct by CSS initial top=-50px, but the slider's visual orientation with appearance:slider-vertical maps min at bottom, so dragging up increases value and submerges crowns — top=water, bottom=air); heureka animation only triggers via a separate button rather than automatically at the end of the slider range; both crowns move identically so the visual difference in displacement is correct in numbers but not spatially distinct.
Slider direction is inverted (value=0 is top/crowns in air which is correct by CSS initial top=-50px, but the slider's visual orientation with appearance:slider-vertical maps min at bottom, so dragging up increases value and submerges crowns — top=water, bottom=air); heureka animation only triggers via a separate button rather than automatically at the end of the slider range; both crowns move identically so the visual difference in displacement is correct in numbers but not spatially distinct.