✓ 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 is top/air, value=100 is bottom/water — HTML range vertical is browser-inconsistent and maps upward drag to lower values, effectively putting water at the top of the slider travel); displaced water calculation uses a nonsensical pixel-ratio formula (divides by 100 cm³ arbitrarily) rather than actual container cross-section, so rising water levels are physically meaningless; no smooth fall animation — crowns teleport via CSS transform; volume and density labels are hardcoded and static rather than truly live.
Slider direction is inverted (value=0 is top/air, value=100 is bottom/water — HTML range vertical is browser-inconsistent and maps upward drag to lower values, effectively putting water at the top of the slider travel); displaced water calculation uses a nonsensical pixel-ratio formula (divides by 100 cm³ arbitrarily) rather than actual container cross-section, so rising water levels are physically meaningless; no smooth fall animation — crowns teleport via CSS transform; volume and density labels are hardcoded and static rather than truly live.