Dark-Numix is a modern flat theme with a combination of light and dark elements, but without the high amount of orange elements of the original Numix. Included are files for cinnamon, gtk-2.0, gtk-3.0 and metacity.
Extract the zip file to the themes directory i.e. ~/.themes
Go to System Settings > Themes and in the "Installed" tab, choose Dark-Numix from the list. After that go to "Other Settings" and choose Dark-Numix on the "Controls" and "Window borders" drop-downs.
Tested on Cinnamon 2.0
Report bugs or contribute at GitHub
License: GPL-3.0+