✓ 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" and max=100 at bottom maps to "water" which is semantically correct for the label, but the vertical range input with slider-vertical renders with 0 at bottom and 100 at top in most browsers, making the physical direction opposite to the label); no smooth fall animation — crowns jump to position on slider drag rather than animating independently.
Slider direction is inverted (min=0 at top maps to "air" and max=100 at bottom maps to "water" which is semantically correct for the label, but the vertical range input with slider-vertical renders with 0 at bottom and 100 at top in most browsers, making the physical direction opposite to the label); no smooth fall animation — crowns jump to position on slider drag rather than animating independently.