Malys is really nice themes and icons creator. Here you can find Malys other themes and icons. This malys-Inversio theme is made for GTK3. There are two versions in this theme gray and white.
You can use these Tools to change theme and icons: Gnome Tweak Tool, Ubuntu Tweak
1st: Install Malys-ex Icons
2nd: Download Wallpapers
To install Malys-Inversio on Ubuntu/Linux Mint open Terminal (Press Ctrl+Alt+T) and copy the following commands in the Terminal: