✓ 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 is inverted (value=0 at top means crowns in air is correct conceptually, but the slider HTML min=0/max=100 with default appearance-slider-vertical renders the minimum at the bottom in most browsers, making top=100%=fully submerged — direction is reversed); mass/volume/density values are static not live, and crown motion jumps instantly with no smooth fall animation.
Slider is inverted (value=0 at top means crowns in air is correct conceptually, but the slider HTML min=0/max=100 with default appearance-slider-vertical renders the minimum at the bottom in most browsers, making top=100%=fully submerged — direction is reversed); mass/volume/density values are static not live, and crown motion jumps instantly with no smooth fall animation.