✓ 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 means air, but HTML range inputs render with 0 at top only via vertical writing-mode which is correct here — however the `writing-mode: bt-lr` with `-webkit-appearance: slider-vertical` actually makes 0 at bottom/water and 100 at top/air, inverting the intended mapping since normalizedValue 1.0 = submerged but slider max is at top visually); no fall animation (crowns jump instantly with no smooth transition between frames driven by time, only position-mapped); splash fires continuously while submerged rather than only at entry moment.
Slider direction is inverted (min=0 at top means air, but HTML range inputs render with 0 at top only via vertical writing-mode which is correct here — however the `writing-mode: bt-lr` with `-webkit-appearance: slider-vertical` actually makes 0 at bottom/water and 100 at top/air, inverting the intended mapping since normalizedValue 1.0 = submerged but slider max is at top visually); no fall animation (crowns jump instantly with no smooth transition between frames driven by time, only position-mapped); splash fires continuously while submerged rather than only at entry moment.