Use Theme's Default Minimize, maximize and close buttons for firefox

[Foad]

hi.
i installed Strata-X for 1909 & 1903 Theme. i want to force Firefox use Theme's Default Buttons for Minimize, maximize and close buttons but i couldn't.
i tried these ways (By firefox Defult skin):

https://www.deviantart.com/dpcdpc11/status-update/18422787?comment=62%3A18422787%3A4828695933
and

https://www.deviantart.com/dpcdpc11/art/Nord-for-Firefox-837860916

how can i fix this?

Thanks.