✓ 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 places crowns at top/air, value=100 drops them down, but the HTML `appearance: slider-vertical` convention means the slider's visual top corresponds to min=0/air — however critically, the two crowns are in *separate* tanks so water displacement is not compared side-by-side in a single vessel as Archimedes did it, and the water level rise calculation is physically nonsensical (both tanks get the same tiny rise despite different displacements, and the base-area math is arbitrary/disconnected from pixel scale), so physics correctness is compromised.
Slider direction is inverted (value=0 places crowns at top/air, value=100 drops them down, but the HTML `appearance: slider-vertical` convention means the slider's visual top corresponds to min=0/air — however critically, the two crowns are in *separate* tanks so water displacement is not compared side-by-side in a single vessel as Archimedes did it, and the water level rise calculation is physically nonsensical (both tanks get the same tiny rise despite different displacements, and the base-area math is arbitrary/disconnected from pixel scale), so physics correctness is compromised.