Top bar menue centering

I have been reading how to’s for this problem.
But I still can’t manage to fix it on my website.

This is the webiste. I would like to have the whole menue with categories,
to be in the center.

I hope you guys can help me out.

https://mrslavic.com.transurl.nl/
note: this is a temp url because I went from wordpress.com to .org, so I am moving my domain.