Can't easily see if I clicked an emoji without hovering to see names of who clicked it

[gregk-git]

Describe the bug:
I can't easily see if a reaction is reacted to by me.

Expected behavior:
In the original GitHub style, because it's white, a reaction normally has a white background, and when you click on it, that becomes like a highlighted blue background. I don't know what colors would work best for your theme, perhaps the number should be white, and I don't know if that should be before or after your react.
Here's screenshots of what I mean with the original style:
Before you react:

After you react:

Where did this happen:
Any repo, but I used #29 to take screenshots to display this.

Steps to reproduce:
React by clicking an emoji on a comment on an issue post.

Screenshots:
Before reacting:

After reacting:

Desktop (please complete the following information):

• OS: Both Windows 10 and ChromeOS
• Browser: Both Firefox and Chrome
• Version: Stable, Beta, and Canary Chrome, and on Version 68.7.0esr (64-bit) of Firefox-ESR

Additional add-ons installed:
Just stylus add-on and your style

[Brettm12345]

This is actually the general background for tooltips. I'm gonna see if I can figure out the css