Evolve is a lightweight and minimal GTK3 theme by Satya and is based on Adwaita theme engine. The theme works well with Gnome Shell 3.2 as well latest Unity in Ubuntu 11.10 as it comes with support for its own custom window controls for maximized windows.
- Extract the zip file. Then extract the tar.gz file to the themes directory i.e. "~/.themes/" or "/usr/share/themes/"
- Now use Gnome Tweak Tool to switch both metacity and GTK Theme.
- If you are using Unity, then logout and relogin.