✓ 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 (min=0 top→air, but writing-mode+direction:rtl flips the visual so dragging down increases value/submersion — functionally correct behavior but semantically the slider_direction_correct mapping is ambiguous; more critically, mass/volume/density live values are static labels, not dynamically updated displays, so live_value_mass/volume/density are false.
Slider direction is inverted (min=0 top→air, but writing-mode+direction:rtl flips the visual so dragging down increases value/submersion — functionally correct behavior but semantically the slider_direction_correct mapping is ambiguous; more critically, mass/volume/density live values are static labels, not dynamically updated displays, so live_value_mass/volume/density are false.