✓ 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 (min=0/top=air is correctly labeled but the HTML range input's visual top maps to max=100/water in vertical mode, so the physical interaction is backwards); ASCII-art rendering is creative but crown position logic has edge-case glitches and there is no smooth fall animation — the crown jumps discretely with slider movement rather than animating independently.
Slider direction is inverted (min=0/top=air is correctly labeled but the HTML range input's visual top maps to max=100/water in vertical mode, so the physical interaction is backwards); ASCII-art rendering is creative but crown position logic has edge-case glitches and there is no smooth fall animation — the crown jumps discretely with slider movement rather than animating independently.