✓ 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 at top maps to crowns in air, but dragging down increases value — the native `writing-mode: bt-lr` / `appearance: slider-vertical` reversal means the physical top of the slider thumb is value 100/submerged, not 0/air); also no smooth CSS/JS fall animation — crowns teleport with slider movement rather than animating independently.
Slider direction is inverted (min=0 at top maps to crowns in air, but dragging down increases value — the native `writing-mode: bt-lr` / `appearance: slider-vertical` reversal means the physical top of the slider thumb is value 100/submerged, not 0/air); also no smooth CSS/JS fall animation — crowns teleport with slider movement rather than animating independently.