Install themes on LibreOffice - in Windows

I saw these two themes


I liked them very much.
How do I use them in Windows? The installation instructions are for Linux only.

Papyrus says:
This project is unmaintained. LibreOffice 5.3 is the last supported version.

I think GTK is a Linux window manager, Windows only allows the built in Microsoft window manager so you have a hard task ahead of you

Have a play with icon themes to find one you like: click Tools - Options - LibreOffice - View and check out the icon themes there