Overwriting css files

Hello
I'm using jevents with the flat view layout. I managed to put the overwritten css file (components/com_jevents/views/flat/assets/css/) at the right place.
There are two other css files I modified:
components/com_jevents/assets/css/jevents.css
media/com_jevents/css/uikit.gsl.min.css
Where do I have to put the overwritten files? I don't have any idea.

Thanks for your help.
Regards
Patrik