I needed a fix for a browser rendering problem. IE and Firefox showed a module in different positions. I spent many hours trying to change css files but could not find the solution. I installed Custom CSS and followed the instructions of their website and the problem was fixed. I was able to set main css for Firefox and create a custom css location for IE affecting only the problem modules on that one page. Thank you, this extension is a life saver. Especially for those non coders among us.