✓ 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/top = crowns in air is correct, but the `writing-mode: bt-lr` + `slider-vertical` renders bottom=0/top=100 in most browsers, so max-end=submerged is correct directionally — however Heureka only fires at exact depth===1 which is slider==100, and mass/volume/density are static labels not live-updating values.
Slider direction is inverted (value=0/top = crowns in air is correct, but the `writing-mode: bt-lr` + `slider-vertical` renders bottom=0/top=100 in most browsers, so max-end=submerged is correct directionally — however Heureka only fires at exact depth===1 which is slider==100, and mass/volume/density are static labels not live-updating values.