Three Simple Dark GTK3 Themes that are easy on the eyes.
These were made in OoMox, therefore, there is support for GTK 3.20 (and before), GTK 2, Openbox etc..
All the credit goes to the OoMox Devs. What a cool little program!
Instead of asking me to change little details, install OoMox and tweak them yourselves. I have provided the Oomox color file for each theme in a ZIP file called ThemeColors.zip. Install OoMox and open it to create its config folder, and place the extracted files (Gandalf, Midnight, Shadow) in your Oomox config folder:
restart Oomox and the themes will be listed on the left.
The Metacity theme I am using in the screenshots is Horst1380's Vertex-Dark (awesome theme!).