CustomCSS 1.3
by Grant
Allow the user to configure custom CSS that will be added to messages when edited
(new, reply and forward). The custom CSS will be added to a newly created <style>
element in the email's head.
About this Add-on
added to all email messages (including replies and forwards) when they
are "composed".
Each time an email is opened in a compose window (write, reply, forward),
the custom CSS will be added to a newly created <style> element in the
email's head. If the head already contains a <style> element that was
added by this extension, it is replaced.