✓ 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 is top/air but mapped via `100 - sliderValue` so crowns actually start at bottom and rise, and the crown placement logic clamps them oddly at waterLevel-2, meaning they never actually enter the water); displaced-water values are static binary (full volume or 0, no partial submersion), and the water-level rise is cosmetically faked rather than physics-derived.
Slider direction is inverted (value=0 is top/air but mapped via `100 - sliderValue` so crowns actually start at bottom and rise, and the crown placement logic clamps them oddly at waterLevel-2, meaning they never actually enter the water); displaced-water values are static binary (full volume or 0, no partial submersion), and the water-level rise is cosmetically faked rather than physics-derived.