✓ 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 (value=0 at top = crowns in air is correct conceptually, but -webkit-appearance:slider-vertical with writing-mode:bt-lr means the slider thumb starts at bottom=0, so top of slider is actually max=100=submerged); mass/volume/density values are static not live; no fall animation, only positional transition; splash fires continuously during drag rather than only at water-entry moment.
Slider direction is inverted (value=0 at top = crowns in air is correct conceptually, but -webkit-appearance:slider-vertical with writing-mode:bt-lr means the slider thumb starts at bottom=0, so top of slider is actually max=100=submerged); mass/volume/density values are static not live; no fall animation, only positional transition; splash fires continuously during drag rather than only at water-entry moment.