My site is Welcome Page. All menu links work, but one “Join/Support the NRA” when it opens has the menu shift. No others do this. I have been over one week trying to resolve this. Can anyone please tell mt how to resolve this? Thank you in advance.
Hi vettenut. Welcome to SitePoint. 
The reason for the apparent menu shift is that on this page (unlike all the others) is not taller than the browser window, and thus a side scroller does not appear. Since that does not appear, the page shifts a little as it disappears.
This is natural behavior, and is common, so it’s not a problem as such. If you want to stop it, you have a couple of choices. Either add some content to that page, or you can force the page to be at least as tall as the browser window.
Thank you! I really appreciate it and learned something