✓ 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 (dragging down = value increases = crowns submerge, but visually the slider top should mean crowns in air; the HTML range input with writing-mode bt-lr means 0 is at bottom, so top of slider = max = fully submerged, which is backwards), and both crowns move together with identical Y offsets rather than independently reflecting their different volumes.
Slider direction is inverted (dragging down = value increases = crowns submerge, but visually the slider top should mean crowns in air; the HTML range input with writing-mode bt-lr means 0 is at bottom, so top of slider = max = fully submerged, which is backwards), and both crowns move together with identical Y offsets rather than independently reflecting their different volumes.