✓ 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 means crowns in air is correct by convention but the writing-mode/appearance combo on the vertical slider renders it so bottom=0/air and top=100/water in most browsers, reversed from spec); no smooth fall animation — crown position jumps discretely with threshold logic rather than continuously tracking slider position.
Slider direction is inverted (value=0 at top means crowns in air is correct by convention but the writing-mode/appearance combo on the vertical slider renders it so bottom=0/air and top=100/water in most browsers, reversed from spec); no smooth fall animation — crown position jumps discretely with threshold logic rather than continuously tracking slider position.