Artisteer Theme header looks and aligns different in Edge/Chrome/Firefox

Hey there,

I’m not a web developer expert at all. This is a project for my friend but there’s one last issue I can’t solve.

The website: http://econtoaudit.hu/

The header image with the numbers aligns different in each browser.
My goal is to set the image length and the menu length to the same. It looks the same in artisteer, but that’s not the case in the actual site.

The image is shorter by 1-2 px on each side than the menu in Chrome.
The image is bigger by 1-2 px on each side than the menu in Edge.
The image is bigger by 2 px on the left side and 1 px on the right side in firefox.

May I ask for some help to resolve this?

Thank you in advance!