Ah, sorry I sent the message the same time as you replied 😉
We are getting closer to a solution. So, I created the mainnav.php in the /templates/ja_company/local/tpls/blocks folder ... and copied into this file your code above... but now the menu is "cut" so that it starts from the middle and goes to the right as you can see in the attached image.
The layout looks like this now:
You can see this, now not so good looking menu, live here: https://confivo.se/
Hope to hear from you soon!