In this tutorial we will help you install the Plastiq GTK 3 theme under Ubuntu 11.10 Oneiric Ocelot. The theme will be appraised by fans of dark colors and is compatible with both Unity and Gnome Shell.
Open the terminal and run this sequence of commands:
wget -O plastiq.tar.gz http://goo.gl/rmAJ4
tar -xzvf plastiq.tar.gz -C ~/.themes
To enable the Plastiq theme, use Gnome Tweak Tool, or run these two commands:
gsettings set org.gnome.desktop.interface gtk-theme 'plastiq'
gconftool-2 --set --type string /apps/metacity/general/theme 'plastiq'
To make the theme more attractive, you can also install an icon theme from this list.