Thanks a lot, many themes, for example this one, also stay on top of my Firefox!

You were very kind to leave me your review.

I thank you very much. I'll tell you that as an artist I'm extremely slow, because I do it in the snippets of time. Something comes out now but will be appreciated in a year, something will not be appreciated at all.
What I can tell you is that if I do a theme it is because it is a source of remembrance of a place, of a person, of a trip, of something I use and therefore of my experience. I am happy that my work is appreciated, I am advantaged by the fact that I have been using Firefox since 2000 !!!

Thank you. I appreciate your review.
شكراً لك. أقدر لك مراجعتك.

Currently firefox doesn't allow me to get to the point of creating a theme background as well (but could I be the one who hasn't succeeded yet); On the web though there are many backgrounds with cubes that you can add in firefox (definitely from version 130 onwards, maybe even earlier). Here I'll explain: On the top right of the firefox homepage there's a little gear icon. Click there and you can change the background to the homepage.
Read more: https://support.mozilla.org/en-US/kb/customize-your-wallpapers

Yes of course you can modify it. Permission is granted already implicitly in the license. You can edit by writing in the description the source and non-profit.

Very kind, thank you