✓ 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 maps to crowns in air and value=100 to water, but with writing-mode+direction rtl the visual top of the slider sends max value, meaning top=water/bottom=air); mass, volume, and density data panel values are static HTML rather than live JS-updated fields, missing the live-update requirement for those three metrics, and there is no fall animation — the crown teleports rather than animates.
Slider direction is inverted (value=0 maps to crowns in air and value=100 to water, but with writing-mode+direction rtl the visual top of the slider sends max value, meaning top=water/bottom=air); mass, volume, and density data panel values are static HTML rather than live JS-updated fields, missing the live-update requirement for those three metrics, and there is no fall animation — the crown teleports rather than animates.