✓ 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 maps to air, but native range input renders with 0 at bottom, putting water-submersion at bottom which is correct mechanically — however using `appearance: slider-vertical` on most browsers the low value is at the bottom meaning slider bottom = air and top = water, inverting the expected direction); mass/volume/density values are hardcoded static text, not live-updating displays; no fall animation (crowns jump instantly via CSS top); splash trigger logic is narrow and unreliable in practice.
Slider direction is inverted (min=0 at top maps to air, but native range input renders with 0 at bottom, putting water-submersion at bottom which is correct mechanically — however using `appearance: slider-vertical` on most browsers the low value is at the bottom meaning slider bottom = air and top = water, inverting the expected direction); mass/volume/density values are hardcoded static text, not live-updating displays; no fall animation (crowns jump instantly via CSS top); splash trigger logic is narrow and unreliable in practice.