A Windows like XFWM4 Theme that supports CSD decorations in GTK3. It comes in three sizes, so it can be used on 4k monitors.
To include the CSD in your theme open the contained gtk-3.0 folder and copy the content into the gtk-3.0 folder of your active/selected theme.
At last, you need to include the provided css file (e.g. csd-winshine.css) into your gtk.css file:
You might have to reselect that theme, or login/logout for CSD to work.