✓ 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 maps to air, but vertical-lr+rtl+slider-vertical CSS may render top as 100% in some browsers, making it unreliable); physics values are plausible with iterative water-rise calculation, but the CM_TO_PX scale factor is arbitrary and disconnected from SVG geometry, so water rise is cosmetically minimal and barely perceptible despite correct math.
Slider direction is inverted (min=0 at top maps to air, but vertical-lr+rtl+slider-vertical CSS may render top as 100% in some browsers, making it unreliable); physics values are plausible with iterative water-rise calculation, but the CM_TO_PX scale factor is arbitrary and disconnected from SVG geometry, so water rise is cosmetically minimal and barely perceptible despite correct math.