✓ 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 (top=air is correct but thumb starts at top=0% meaning air, yet crown movement math maps 0%→top of container and 100%→water correctly — however the label layout says "Luft" at top and "Wasser" at bottom which is correct, but there is no smooth fall animation; crowns teleport to position without a timed drop sequence, and splash particles fire continuously during drag rather than only at water-entry moment.
Slider direction is inverted (top=air is correct but thumb starts at top=0% meaning air, yet crown movement math maps 0%→top of container and 100%→water correctly — however the label layout says "Luft" at top and "Wasser" at bottom which is correct, but there is no smooth fall animation; crowns teleport to position without a timed drop sequence, and splash particles fire continuously during drag rather than only at water-entry moment.