Load global css and javascript files

Hey guys hope you are doing well,
I am looking to change some stuff on the mautic design and on the campaign section.

I am trying to find a way to load globaly css and javascript file that will load on top of every page on mautic. I also need to load it in a way that won’t stop work after every update.

At the moment i am required to hardcode it into the files and each update remove the code.
Is there a better way (and simple one) to do it?