Rated 2 out of 5 stars

Tried this extension on a TB 128.3.3esr, KDE with dark theme (including entirely white-on-black TB), read+write e-mails as plaintext only. E-mails would previously print(-preview) black-on-white (i.e., OK for printing and readable).

After installation, print preview shows white fonts on white (body) / selected color (headers) background, regardless of whether TB's override-with-manually-configured-colors was set to "always" or "never".

Deactivated extension, no change. Uninstalled it, still no change. I had to manually delete settings out of prefs.js, *including non-extension-specific ones*, to get the original behavior back.

BACKUP YOUR TB CONFIG before trying this extension.