Color line quotes

Is there a way to make the line of quoted text of different colors?
Below is the same email opened in Mailspring and Thunderbird.





Having the colors would be pretty helpful when looking at emails in mailing lists, since there are so many levels of nesting.

(Originally posted by darwin67 on GitHub.)

Hey! I think we can definitely do this—do you know offhand if this is an option in Thunderbird or if it does this all the time? I think we copied Gmail’s behavior for Mailspring but some CSS rules would probably allow us to do this.

(Originally posted by bengotow on GitHub.)

I think it does it all the time.
Can’t find the settings to tune the behavior.

(Originally posted by darwin67 on GitHub.)