✓ 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 maps to crowns in air but slider thumb sits at top only by default; more critically the slider uses writing-mode bt-lr without reversing min/max, so dragging down increases depth — directionally ambiguous/broken in most browsers); physics units are wrong (buoyancy reported in "mN" but calculated as cm³·g/cm³·9.81 = gram-force, not millinewtons), and displaced-volume calculation uses an ad-hoc 1.5× ratio rather than a proper sphere-cap formula.
Slider direction is inverted (value=0 maps to crowns in air but slider thumb sits at top only by default; more critically the slider uses writing-mode bt-lr without reversing min/max, so dragging down increases depth — directionally ambiguous/broken in most browsers); physics units are wrong (buoyancy reported in "mN" but calculated as cm³·g/cm³·9.81 = gram-force, not millinewtons), and displaced-volume calculation uses an ad-hoc 1.5× ratio rather than a proper sphere-cap formula.