I was editing Default.php file under styles directory where most of the CSS for Default theme is and suddenly I realize that while Firefox still display the page properly, it’s all messed up under IE9 and Chrome.

I see nothing wrong in what I edited!  Anyone else had similar experiences editing CSS?

I was able to solve this by using the SP Theme Editor from admin panel and only click Update file.  I looked at th filze size before and after and there was a few bytes added (but what!?).  I don’t know if the editor I use is causing the problem?