Lightbox Move all the site

Hey guys.
Im designing a new website.
for some reason when i’m using light box and click it its move all the website to the right when its open the lightbox.
this problem its happen anytime in any website i used Lightbox.
For example - in this website its happen.

and you can see it also here is my site Read-Only (On the portfolio - link number 2 from the right in the menu) at the logos (link number 2 from the right - the orange one):

Hi @Maor_Naim

The best explanation i’ve found for this occurring is:

Thanks to @rileyrichter for the link a while back