✓ 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 (hint reads "⬆ Luft / ⬇ Wasser" but the writing-mode/direction CSS causes the native thumb to move opposite to expectation on most browsers), penalizing slider UX; otherwise a thorough, well-implemented demo with correct physics, particle splashes, animated Heureka overlay, and live readouts.
Slider direction is inverted (hint reads "⬆ Luft / ⬇ Wasser" but the writing-mode/direction CSS causes the native thumb to move opposite to expectation on most browsers), penalizing slider UX; otherwise a thorough, well-implemented demo with correct physics, particle splashes, animated Heureka overlay, and live readouts.