i found out today the "web developer" add on for Firefox.
This add-on gives the posibility of editing the CSS code of my pages with an editor that appears at the botton of the Firefox window and split second after see the change directly in Firefox. It is very confortable! I don't have to save the code with the editor and then refresh the browser!
Do you know any open source app which do this with CSS and other languages? You know, an app with and editor and a browser that shows what you write while you write.