gtk themes for XFCE
XFCE Says:
https://docs.xfce.org/xfce/xfce4-settings/appearance
Get a Theme
Pick one such as: https://www.gnome-look.org/p/1267246 or https://www.xfce-look.org/p/1357889
Download into ~/.themes
- create .themes if it doesn’t exist
- Download the entire xz zip file into .themes
Configure the Theme
Setting > Appearance > Add (click on the xz file).