✓ 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 puts crowns high in air which is correct, but the CSS background gradient goes blue-at-bottom to gray-at-top suggesting semantic confusion; more critically the crown positioning math moves crowns upward as slider increases, so high slider value = low on screen = water, which is actually correct directionally — but no genuine fall animation exists, crowns simply teleport via CSS transition, and splash effects fire continuously while partially submerged rather than only on entry.
Slider direction is inverted (value=0 at top puts crowns high in air which is correct, but the CSS background gradient goes blue-at-bottom to gray-at-top suggesting semantic confusion; more critically the crown positioning math moves crowns upward as slider increases, so high slider value = low on screen = water, which is actually correct directionally — but no genuine fall animation exists, crowns simply teleport via CSS transition, and splash effects fire continuously while partially submerged rather than only on entry.