A theme for Ulauncher that based on the Ubuntu Ambiant-MATE and Ambiant-MATE-Dark themes that ship with Ubuntu MATE. This is just a fork of https://github.com/pizzadude/ulauncher-mint-y-dark-theme, which I used as a template and followed the instructions here to give it my own CSS.
Copy or git clone this repo to ~/.config/ulauncher/user-themes/