I was having problems with a theme for Thunderbird using monospace font if "format=flowed" was not present in the content-type of a header for a message I was reading. I commented out these lines in messageBody.css in that theme, and the result was that serif font is used no matter what is in the content-type.
Just what do these lines do that removing them would make such a difference?
Code:
@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
@namespace html url("http://www.w3.org/1999/xhtml");