✓ 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 the vertical slider's visual top corresponds to max, so dragging down raises value — crowns move from air toward water as slider increases, which is technically correct in value mapping but the `writing-mode: bt-lr` and `slider-vertical` appearance means the physical top of the slider track is actually max=100/water, making it inverted UX); no genuine fall animation (crown jumps discretely via ASCII re-render rather than animating), and splash is randomized noise rather than a real effect.
Slider direction is inverted (min=0 at top maps to crowns in air, but the vertical slider's visual top corresponds to max, so dragging down raises value — crowns move from air toward water as slider increases, which is technically correct in value mapping but the `writing-mode: bt-lr` and `slider-vertical` appearance means the physical top of the slider track is actually max=100/water, making it inverted UX); no genuine fall animation (crown jumps discretely via ASCII re-render rather than animating), and splash is randomized noise rather than a real effect.