✓ 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 is top/air, value=100 is bottom/water, which maps correctly in logic but the slider's visual orientation with writing-mode bt-lr means the physical thumb is at the bottom when value=0, so "top" of the slider corresponds to fully submerged — however, examining the CSS with writing-mode bt-lr the low value IS at the bottom visually, which means bottom=air, top=water, making slider_direction_correct false); splash fires repeatedly on any downward movement rather than once at water-surface entry, and the water-level rise visual effect is subtle but present.
Slider direction is inverted (value=0 is top/air, value=100 is bottom/water, which maps correctly in logic but the slider's visual orientation with writing-mode bt-lr means the physical thumb is at the bottom when value=0, so "top" of the slider corresponds to fully submerged — however, examining the CSS with writing-mode bt-lr the low value IS at the bottom visually, which means bottom=air, top=water, making slider_direction_correct false); splash fires repeatedly on any downward movement rather than once at water-surface entry, and the water-level rise visual effect is subtle but present.