CSS to change category colors isn't working (yet!)

I was very excited to see the FAQs now include easy color-coding of categories; however, I haven’t been able to get it to work.

I have a post category called “Twitter” that I’d like to color blue.

Based on the FAQs, here’s the initial CSS I added to my child theme style sheet:

.post.twitter {
    color: blue;
}

However, the post text color stays grey.

I’ve tried the following, which have not worked:

1) Adding !Important after the color in CSS
2) Opening Inspect Element to see what classes are governing the post. Note, the grey text color is being inherited from “body” and there is no indication of CSS for blue even being overridden.
3) Editing child CSS for all possible versions of the full class for this post:

.post.draft.twitter.ui-draggable-handle.draggable

What step(s) am I missing to be able to color code calendar entries based on post category? Thanks!

https://wordpress.org/plugins/editorial-calendar/