✓ 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
Impressively complete implementation with correct physics (gold 19.3 g/cm³, alloy 13.0 g/cm³, same 1000 g mass), working custom SVG slider drag, splash particles, water rise, live displaced-water readout, and Heureka animation — but the slider is a custom SVG drag (not a native range input) with a narrow grab target and no keyboard/accessibility support, mass/volume/density values in the panels are static labels rather than fully live-updating tspans, and the level-rise pixel annotation ("px") is a slightly awkward proxy for the true volumetric comparison.
9,649 output tokens · claude-opus-4-6 · end_turn
Impressively complete implementation with correct physics (gold 19.3 g/cm³, alloy 13.0 g/cm³, same 1000 g mass), working custom SVG slider drag, splash particles, water rise, live displaced-water readout, and Heureka animation — but the slider is a custom SVG drag (not a native range input) with a narrow grab target and no keyboard/accessibility support, mass/volume/density values in the panels are static labels rather than fully live-updating tspans, and the level-rise pixel annotation ("px") is a slightly awkward proxy for the true volumetric comparison.