✓ 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 = crowns in air at top is correct but the slider renders visually bottom-to-top with writing-mode bt-lr, yet crown motion is `top: 30 + depth*3` which moves crowns down as slider increases — however there is no fall animation, both crowns share the same single water container and the plated crown's `margin-left:250px` pushes it entirely outside the visible container, breaking the visual layout; splash fires on every input event in the 0–25% range rather than only on entry.
Slider direction is inverted (value=0 = crowns in air at top is correct but the slider renders visually bottom-to-top with writing-mode bt-lr, yet crown motion is `top: 30 + depth*3` which moves crowns down as slider increases — however there is no fall animation, both crowns share the same single water container and the plated crown's `margin-left:250px` pushes it entirely outside the visible container, breaking the visual layout; splash fires on every input event in the 0–25% range rather than only on entry.