✓ 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 air, but the appearance label says LUFT at top yet slider-vertical on most browsers renders max at top, making direction ambiguous/broken), density display is physically nonsensical during transition (it divides fixed mass by partially-submerged volume rather than true crown volume), mass is static/hardcoded not a live displayed value, fall animation is absent (crowns jump via transform with no tween), and splash effects fire randomly during the entire slider range rather than only at water-entry moment.
Slider direction is inverted (value=0 at top maps to air, but the appearance label says LUFT at top yet slider-vertical on most browsers renders max at top, making direction ambiguous/broken), density display is physically nonsensical during transition (it divides fixed mass by partially-submerged volume rather than true crown volume), mass is static/hardcoded not a live displayed value, fall animation is absent (crowns jump via transform with no tween), and splash effects fire randomly during the entire slider range rather than only at water-entry moment.