Nav Header on Safari (Large Viewports) Expands to Viewport Height

Hi,

Looking on Safari (on viewports over 900px), I can see that my site navigation bar is expanding to fit the full height of the viewport. Everything works fine on mobile once it hits the breakpoint, and on Chrome, where there doesn't appear to be any issues.

Screenshot with Safari top window, & Chrome bottom window:
https://ibb.co/kym00D3

My test website is: https://scanemedia-test.xyz/

Can't figure this one out, so would really appreciate some help.

Thanks,
Brian