I would suggest you read: IcingaWeb 2.10 can't render my stylesheet with media query, or is only in dark mode
after that you should be able to fix your company theme. or open an new topic with your work, maybe someone is going to help?
you should also fork icingaweb2-theme-company and create a pull request with your changes.
don’t be afraid of less, it’s simply, and it’s never to late for a webdeveloper to learn something new 