Since there isn't a specific CSS Override tutorial, I've tried my best to mimic Easyblog tutorial.

In Easyblog, it says to insert style.css file in here or create the path:
/templates/mytemplate/html/com_easyblog/css/

In Easydiscuss, I have put style.css file and created the path:
/templates/mytemplate/html/com_easydiscuss/css/

I've made a slight change to the nav toolbar color to aqua to test, and I after emptying cache and refreshing browser, I see no changes.

What could be wrong?