My CSS file that I think looks nice!
In order to install this to your XFCE desktop, check that you have the config file. For good measure, type
mkdir .config/gtk-3.0
If it results in an error stating the directory exists, or no error at all, then you are ready to continue
Enter:
cd ~/.config/gtk-3.0
git clone ...
Yay! You have installed my theme! Enjoy.