If you are a git user, you can install the theme by cloning the repo:
$ git clone https://github.com/getomni/gedit.git
Download using the GitHub .zip download option and unzip them.
- Copy
omni.xml
to~/.local/share/gedit/styles/
- Open Gedit
- Go to Edit > Preferences > Fonts & Colors
- Select Omni under the Color Scheme section