✓ 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 = air, but transform: rotate(180deg) flips the visual so top visually maps to bottom of range), crown movement math is broken (regex extracts only x coordinate, so y-position resets to x-value on each update), and density values are physically implausible for a gilded crown (10.5 g/cm³ is silver-range, not a realistic gold-alloy blend).
Slider direction is inverted (value=0 at top = air, but transform: rotate(180deg) flips the visual so top visually maps to bottom of range), crown movement math is broken (regex extracts only x coordinate, so y-position resets to x-value on each update), and density values are physically implausible for a gilded crown (10.5 g/cm³ is silver-range, not a realistic gold-alloy blend).