✓ 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 labeled AIR at top, max=100 labeled WATER at bottom, but HTML range sliders with vertical writing-mode render visually flipped — top of thumb actually emits high values, making bottom=air and top=water in practice); all other features are well-implemented with correct physics (gold 19.3 g/cm³, fake 8.5 g/cm³, same 1000g mass), live readouts, rising water, splash particles, and a polished Heureka overlay.
Slider direction is inverted (min=0 labeled AIR at top, max=100 labeled WATER at bottom, but HTML range sliders with vertical writing-mode render visually flipped — top of thumb actually emits high values, making bottom=air and top=water in practice); all other features are well-implemented with correct physics (gold 19.3 g/cm³, fake 8.5 g/cm³, same 1000g mass), live readouts, rising water, splash particles, and a polished Heureka overlay.