✓ 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, which is correct linguistically, but -webkit-appearance:slider-vertical renders the thumb at bottom for min, so bottom=air/top=water in practice); mass/volume/density values are static (not live), no fall animation — crowns teleport rather than animate.
Slider direction is inverted (min=0 at top maps to air, which is correct linguistically, but -webkit-appearance:slider-vertical renders the thumb at bottom for min, so bottom=air/top=water in practice); mass/volume/density values are static (not live), no fall animation — crowns teleport rather than animate.