✓ 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 maps to 0% immersion which is correct conceptually, but the CSS `rotate(180deg)` combined with `writing-mode: vertical-lr` means the physical top of the slider produces the maximum value — the crown is in water at the top position — making direction incorrect; no fall/splash animations, ASCII-only rendering with a single ♛ character that doesn't visually demonstrate the crowns entering water with any realism.
Slider direction is inverted (value=0 at top maps to 0% immersion which is correct conceptually, but the CSS `rotate(180deg)` combined with `writing-mode: vertical-lr` means the physical top of the slider produces the maximum value — the crown is in water at the top position — making direction incorrect; no fall/splash animations, ASCII-only rendering with a single ♛ character that doesn't visually demonstrate the crowns entering water with any realism.