✓ 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 (slider min=0 maps to crowns in air, max=100 to submerged, but the vertical slider's visual top corresponds to value=0/air — this may render correctly browser-dependently via writing-mode tricks, but the semantic mapping is ambiguous and no smooth fall animation plays independently; crowns jump position only on slider drag with no autonomous drop sequence.
Slider direction is inverted (slider min=0 maps to crowns in air, max=100 to submerged, but the vertical slider's visual top corresponds to value=0/air — this may render correctly browser-dependently via writing-mode tricks, but the semantic mapping is ambiguous and no smooth fall animation plays independently; crowns jump position only on slider drag with no autonomous drop sequence.