✓ 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 = air is correct in label but slider-vertical orientation may render bottom=0, and the crown positioning logic maps fraction=0 to "just above water" and fraction=1 to "fully submerged" which is correct conceptually, but mass/volume/density live values are static HTML, not dynamically updated — only displaced water and buoyancy update live.
Slider direction is inverted (value=0 top = air is correct in label but slider-vertical orientation may render bottom=0, and the crown positioning logic maps fraction=0 to "just above water" and fraction=1 to "fully submerged" which is correct conceptually, but mass/volume/density live values are static HTML, not dynamically updated — only displaced water and buoyancy update live.