Numix Solarized Dark is a modification of the Numix Solarized theme by bitterologist which is based on the Numix theme by Satyajit Sahoo (satyajit.happy@gmail.com).
In Numix Solarized Dark, all light elements are replaced by dark ones.
Extract the zip file to the themes directory i.e. /usr/share/themes/
To set the theme in Gnome, run the following commands in Terminal,
gsettings set org.gnome.desktop.interface gtk-theme "Numix"
gsettings set org.gnome.desktop.wm.preferences theme "Numix"
To set the theme in Xfce, run the following commands in Terminal,
xfconf-query -c xsettings -p /Net/ThemeName -s "Numix"
xfconf-query -c xfwm4 -p /general/theme -s "Numix"
GTK+ 3.6 or above
Murrine theme engine
License: GPL-3.0+