✓ 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 puts crowns at top/air, value=100 moves them down into water — actually correct on re-read — but the slider is styled as vertical with appearance:slider-vertical which renders as horizontal in most browsers, and there is no continuous fall animation; crowns teleport to position on each slider event rather than animating smoothly, and splash detection is unreliable due to the discrete-event-only update model.
Slider direction is inverted (value=0 puts crowns at top/air, value=100 moves them down into water — actually correct on re-read — but the slider is styled as vertical with appearance:slider-vertical which renders as horizontal in most browsers, and there is no continuous fall animation; crowns teleport to position on each slider event rather than animating smoothly, and splash detection is unreliable due to the discrete-event-only update model.