✓ 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, which appears correct conceptually, but label reads "↓ Wasser" at bottom and crown displacement logic is broken: submerged fraction only triggers when newCrownY > WATER_SURFACE_Y=350 but crown starts at Y=80 and moves down 250px max reaching Y=330, never crossing 350, so crowns never actually enter the water, displaced water stays 0, water never visibly rises, and the gilded-displaces-more visual check therefore always fails.
Slider direction is inverted (value=0 at top maps to crowns in air, which appears correct conceptually, but label reads "↓ Wasser" at bottom and crown displacement logic is broken: submerged fraction only triggers when newCrownY > WATER_SURFACE_Y=350 but crown starts at Y=80 and moves down 250px max reaching Y=330, never crossing 350, so crowns never actually enter the water, displaced water stays 0, water never visibly rises, and the gilded-displaces-more visual check therefore always fails.