This is a HUGE deal. You've broken many sites internally that my company uses and that I maintain. This is a problem that affects all pages and breaks how CSS behaves. Here's a link to a site with a specific code example that shows off this bug: http://krakrjak.blogspot.com/2012/01/firefox-901-font-css-bug.html

Please fix this so I can quit answering questions about why our sites are broken in what appears to be the most popular browser at the company.

Thank you!

No one from Mozilla has responded to this even though it continues to be a PITA. A bug has been opened on this issue at https://bugzilla.mozilla.org/show_bug.cgi?id=718016

If you are interested in getting this bug fixed please go to bugzilla.mozilla.org and vote for bug 718016.

The css in the blogpost http://krakrjak.blogspot.com/2012/01/firefox-901-font-css-bug.html is wrong, and that is why this does not work in Firefox. To access a class you must use the class selector (a dot). For example: .p-inner p { }
You can go to Mozilla Developer Network to learn CSS.
https://developer.mozilla.org/en-US/learn/css

I see what you mean. So using the # notation (id selector) instead of using the correct . notation (class selector) lead to this issue for me. It just appears that FireFox got a little more strict around the standard and that means the code I am maintaining is full of non-standard CSS that I will have to fix up now... ooh well.

Interestingly enough this worked up until 9.0. I do see that this is not valid CSS now. Thanks for the link.

There still seems to be an issue that Dan is tracking down that is separate from my misuse of CSS.

I have updated the blog post to show what the issue with my CSS is and how to avoid the issue and write correct CSS in this respect.

http://krakrjak.blogspot.com/2012/01/firefox-901-font-css-bug.html