✓ 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 labels say "⬆ Luft / ⬇ Wasser" but a vertical range input with writing-mode:vertical-lr/direction:rtl and value=0 at rest means dragging down increases value, making top=air correct in label intent yet the CSS rendering is browser-inconsistent; splash fires for both crowns simultaneously at the same threshold rather than sequentially, and both submerge at an identical ratio, masking the volume difference visually during descent.
Slider direction is inverted (hint labels say "⬆ Luft / ⬇ Wasser" but a vertical range input with writing-mode:vertical-lr/direction:rtl and value=0 at rest means dragging down increases value, making top=air correct in label intent yet the CSS rendering is browser-inconsistent; splash fires for both crowns simultaneously at the same threshold rather than sequentially, and both submerge at an identical ratio, masking the volume difference visually during descent.