Bug : overlay causing blank white page

Hi,

If i let the overlay (box uncheched) on my popup item, the page become totally white as soon as the popup appears.
If i remove the overlay (check the box) the pages displays normally but no popup is displayed : https://www.binhas.info/les-bonnes-questions-a-se-poser-pour-une-installation-reussie/

Can you please help ?
Thank you very much