✓ 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 crowns in air correctly by label, but the `writing-mode: bt-lr` / `appearance: slider-vertical` approach is non-standard and behaves inconsistently across browsers; more critically, no fall animation exists — the crown teleports rather than animating, and Eureka only appears at depth=100 with a CSS animation that immediately fades out, providing poor UX.
Slider direction is inverted (value=0 at top maps to crowns in air correctly by label, but the `writing-mode: bt-lr` / `appearance: slider-vertical` approach is non-standard and behaves inconsistently across browsers; more critically, no fall animation exists — the crown teleports rather than animating, and Eureka only appears at depth=100 with a CSS animation that immediately fades out, providing poor UX.