Nav Bar Moving on Page Load

Hi there,

So I am having an issue with a nav bar for a site where for some reason when I click on a link in the nav bar the contents move to the right when the new page begins to load. Once it is loaded they center themselves again, but I cannot figure out for the life of me why this is happening.

If anyone can help with this mystery that would be awesome, I have the published link and the read-only link below.

Published Link:

Read-only Link:

Here is my site Read-Only:
(how to share your site Read-Only link)