✓ 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 — the label says "⬆ Rein / ⬇ Raus" but with writing-mode+direction:rtl the thumb-up position maps to value=0 (crowns out), making the semantic direction counter-intuitive; otherwise a richly featured, physically accurate demo with solid splash/bubble/Heureka animations and well-populated live readouts.
Slider direction is inverted — the label says "⬆ Rein / ⬇ Raus" but with writing-mode+direction:rtl the thumb-up position maps to value=0 (crowns out), making the semantic direction counter-intuitive; otherwise a richly featured, physically accurate demo with solid splash/bubble/Heureka animations and well-populated live readouts.