How to stylize administration colours ?

Hi is possible change colours in administration ? I cant change it via CSS and via !important. Nothing change.

.Button--primary { and .App-header, .App-header a {

Thanks

I assume you used the option in Appearance > Edit Custom CSS? This is only meant for the front end. Changes there won't reflect on the backend / admin area. If you want to change something there I'd recommend this discussion pointing to a solution: https://discuss.flarum.org/d/21490-custom-css-for-admin-area-or