✓ 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/top=air is correct in HTML semantics but vertical-lr + direction:rtl makes slider-top=100=water, slider-bottom=0=air on most browsers); buoyancy unit label says "mN" in CSS but code outputs "N" — minor inconsistency; otherwise excellent completeness with particle heureka, ripple/splash effects, dual canvas, live physics cards, and correctly differentiated densities/volumes.
Slider direction is inverted (min=0/top=air is correct in HTML semantics but vertical-lr + direction:rtl makes slider-top=100=water, slider-bottom=0=air on most browsers); buoyancy unit label says "mN" in CSS but code outputs "N" — minor inconsistency; otherwise excellent completeness with particle heureka, ripple/splash effects, dual canvas, live physics cards, and correctly differentiated densities/volumes.