Griffin BOLT is an flat and modern theme for GNOME, unity and other linux environments. It gives the desktop a user friendly look.
Extract the zip file to the themes directory i.e. `/usr/share/themes/` or `~/.themes/` (create it if necessary).
To set the theme in Gnome, run the following commands in Terminal.
gsettings set org.gnome.desktop.interface gtk-theme "Griffin-BOLT"
gsettings set org.gnome.desktop.wm.preferences theme "Griffin-BOLT"
or Change via distribution specific tool such as unity tweak tool and GNOME tweak tool.