✓ 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 crown in air via 100-sliderValue logic, but the slider's native vertical orientation with min=0/max=100 and writing-mode bt-lr means dragging up increases value, so top of slider = water/submerged, bottom = air — opposite of spec); mass, volume, and density values are static HTML text rather than live JS-updated displays, only displaced water updates live.
Slider direction is inverted (value=0 at top puts crown in air via 100-sliderValue logic, but the slider's native vertical orientation with min=0/max=100 and writing-mode bt-lr means dragging up increases value, so top of slider = water/submerged, bottom = air — opposite of spec); mass, volume, and density values are static HTML text rather than live JS-updated displays, only displaced water updates live.