[Users] how to darken Claws-mail windows?

[Pierre A.]

I use Fedora 36, Gnome 42.4, Claws mail 4.1.0.  

Claws mail windows are all white and dazzle me.
How to darken them ?

In Ubuntu, Claws mail windows are dark.

Gnome theme settings are unfortunately not effective on Claws-mail.

Thanks for hints.