✓ 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
All 21 requested features are implemented with correct physics (gold 19.3 g/cm³, gilded 5.5 g/cm³, same 1000 g mass), polished canvas rendering with ripples/bubbles/splashes, and a well-styled Heureka overlay — minor flaw is that the slider resets splash flags on every move causing repeated splash re-triggers when scrubbing backward and forward.
All 21 requested features are implemented with correct physics (gold 19.3 g/cm³, gilded 5.5 g/cm³, same 1000 g mass), polished canvas rendering with ripples/bubbles/splashes, and a well-styled Heureka overlay — minor flaw is that the slider resets splash flags on every move causing repeated splash re-triggers when scrubbing backward and forward.