Update custom fork

[faselunare]

Hi, I'm working on a local version of svgedit to customize the UI and add custom function.
Now I see few update that I want to apply to my local version without loosing my modification.
Is it possible?

My local version is hooked to my personal gitlab and not to the svgedit git

Since my modification is mainly CSS and component mods (panels for example)
Is it possible to have a sort of theming function and extension function to add my custom functions?

Thanks