✓ 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 maps to crowns in air, but HTML range inputs render max at top when vertical — crowns actually start in air at value=0 which is the bottom thumb position, making the direction semantically reversed); no smooth fall animation, crowns teleport linearly with no physics-based drop; water level rise and displaced-water math use a simplified but directionally correct model.
Slider direction is inverted (value=0 at top maps to crowns in air, but HTML range inputs render max at top when vertical — crowns actually start in air at value=0 which is the bottom thumb position, making the direction semantically reversed); no smooth fall animation, crowns teleport linearly with no physics-based drop; water level rise and displaced-water math use a simplified but directionally correct model.