✓ 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 per label (hint says ▲ Air / ▼ Water but slider value=0 maps to crowns in air at the top, which is technically correct directionally — however the `writing-mode: vertical-lr; direction: rtl` CSS combo makes the physical slider thumb sit at the bottom when value=0, meaning the thumb-bottom=air and thumb-top=water, inverting the expected UX; all physics values (VOL_GOLD≈51.8 cm³, VOL_FAKE≈161.3 cm³) are correct and the gilded crown visibly displaces more water.
Slider direction is inverted per label (hint says ▲ Air / ▼ Water but slider value=0 maps to crowns in air at the top, which is technically correct directionally — however the `writing-mode: vertical-lr; direction: rtl` CSS combo makes the physical slider thumb sit at the bottom when value=0, meaning the thumb-bottom=air and thumb-top=water, inverting the expected UX; all physics values (VOL_GOLD≈51.8 cm³, VOL_FAKE≈161.3 cm³) are correct and the gilded crown visibly displaces more water.