Error message: "There are no rules. You can create a rule." What does it mean?

[Thomas Kehoe]

I'm trying to find the CSS for a line in my website. I opened the CSS tab in the Firebug console. I move the mouse around on my webpage. The Firebug window also shows the same error message: "There are no rules. You can create a rule." What does this mean? How do I fix the problem? How can I see the CSS styles on my website? I have Firebug 1.12.1 and Firefox 24. Is there documentation that explains how to use the Firebug CSS tab? I looked at "https://getfirebug.com/css" but it just tells you the features of Firebug's CSS tabs, not how to get it to work.

[Sebastian Zartner]

The documentation of the CSS panel can be found in our wiki:

https://getfirebug.com/wiki/index.php/CSS_Panel

The message "There are no rules. You can create a rule." means that the page doesn't contain any CSS.
If you're sure it does, it may be a problem in Firebug. In this case please provide a URL, so we can reproduce your issue on our machines.

Sebastian