✓ 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
Exceptionally complete implementation with correct physics (ρ_gold=19.3, ρ_fake=8.5, same 1000g mass), animated water rise proportional to displaced volume, particle splash, Heureka overlay with fade-in scale animation, ripple surface, force arrows, and volume bars — only notable flaw is the easing on the slider mapping (easeInOutCubic applied to raw slider value) which makes crown motion feel non-linear relative to slider position and the water-rise scaling constant (0.38 px/cm³) is empirical rather than tank-geometry-derived, slightly misrepresenting true rise ratio between the two tanks.
Exceptionally complete implementation with correct physics (ρ_gold=19.3, ρ_fake=8.5, same 1000g mass), animated water rise proportional to displaced volume, particle splash, Heureka overlay with fade-in scale animation, ripple surface, force arrows, and volume bars — only notable flaw is the easing on the slider mapping (easeInOutCubic applied to raw slider value) which makes crown motion feel non-linear relative to slider position and the water-rise scaling constant (0.38 px/cm³) is empirical rather than tank-geometry-derived, slightly misrepresenting true rise ratio between the two tanks.