✓ 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 at top means air, value=100 at bottom means submerged, which matches correct direction semantically, but -webkit-appearance:slider-vertical renders vertically reversed so top thumb = max = water, effectively inverting UX); crown rendering uses plain circles rather than crown shapes, and the water-rise calculation uses an arbitrary scaling factor instead of proper container cross-section area.
Slider direction is inverted (value=0 at top means air, value=100 at bottom means submerged, which matches correct direction semantically, but -webkit-appearance:slider-vertical renders vertically reversed so top thumb = max = water, effectively inverting UX); crown rendering uses plain circles rather than crown shapes, and the water-rise calculation uses an arbitrary scaling factor instead of proper container cross-section area.