✓ 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 is a custom-draggable div (not a native range input), direction is correct and crowns do move, but physics are broken — volumes are tiny (≈0.52 and 0.95 cm³) yet water rise uses an inconsistent formula that barely reacts; density is shown as a static label rather than a live computed value; and the water-level rise of ~0.001 mm makes the displacement visualization practically invisible.
Slider is a custom-draggable div (not a native range input), direction is correct and crowns do move, but physics are broken — volumes are tiny (≈0.52 and 0.95 cm³) yet water rise uses an inconsistent formula that barely reacts; density is shown as a static label rather than a live computed value; and the water-level rise of ~0.001 mm makes the displacement visualization practically invisible.