✓ 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 means air, but vertical slider with bt-lr writing-mode makes bottom=0/air and top=100/water in most browsers); no smooth fall animation — crown teleports rather than animating; splash fires repeatedly on every input event in the 0–10% range rather than once on entry.
Slider direction is inverted (min=0 at top means air, but vertical slider with bt-lr writing-mode makes bottom=0/air and top=100/water in most browsers); no smooth fall animation — crown teleports rather than animating; splash fires repeatedly on every input event in the 0–10% range rather than once on entry.