How to get navbar on one line with keeping slideshow center

Site URL: https://www.northwoodsfarmny.com/

I am having trouble getting my navigation bar on one line while keeping my slideshow below it center on different displays.

I was using the code 

.header-nav-list {
     flex-wrap: nowrap !important;
}

but when I do it throws off the formatting on the site and nothing seems to stay center on multiple displays? I attached an image to show what it looks like with this code and without.

If anyone could give me a little insight it would be very much appreciated! 

Password: password