Understanding CSS for user styling in a browser

Question

I want to make a specific change to the appearance of a specific site in my web browser. This site uses CSS, so I think what I should do is write a user CSS override (please correct me if this is wrong).

My browsers are Firefox (for which I think I should write something in chrome/userContent.css) and Chrome (User\ StyleSheets/Custom.css).

The specific change I want to make is to remove the background pattern (dark dots) on all pages of http://unix.stackexchange.com/ . But more generally, please teach me how to fish: how do I find out what parameter to change, and how do I write this change in a user css?

Answer 1

You do what you would do if you were putting on the site "foo.bar { background-pattern:none; }" then add !important before the }. Here's a little detail on non user-css use that still explains it for your use. http://www.yellowjug.com/web-design/the-importance-of-important-in-css/

Answer 2

Install firebug to identify the relevant CSS property and then write a greasemonkey script to override it.