✓ 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 at top = crowns in air is correct conceptually, but the vertical slider renders with value=0 at the bottom due to writing-mode:vertical-lr without proper inversion, making it functionally backwards); otherwise a feature-complete, visually polished implementation with correct physics, animated falling crowns, rising water, splash particles, bubbles, and a Heureka overlay.
Slider direction is inverted (min=0 at top = crowns in air is correct conceptually, but the vertical slider renders with value=0 at the bottom due to writing-mode:vertical-lr without proper inversion, making it functionally backwards); otherwise a feature-complete, visually polished implementation with correct physics, animated falling crowns, rising water, splash particles, bubbles, and a Heureka overlay.