CSS is case sensitive

Never thought Cascaded Style Sheets will be case sensitive. After a long time of coding in VB, and ASP, using Visual Studio 2005; I was kind of accustomed to coding in whatever case I wanted and wait for the VS2005 to take care of the case. Lately I have been having this problem in viewing the image button, incorrectly. the problem was further aggreivated, when there were two similar buttons with one showing the background image and the other one completely blank. After about an hour of excercise, with the stylesheet, I found out that I was writing one as Jobs_Feature and the other one as Jobs_feature. Bingo! Probably a lesson learnt hard way, but then i prefer to learn it this way rather than keep on reading books and trying to memorize
the facts and features of the stuff.

Further research shows that if the doctype declaration in the start of HTML page is not defined as XML, then CSS does not mind the different case in the class name, but the moment we declare the XML doctype, it turns out to be case sensitive. So this property of CSS can be attributed to XML. If you remember, XML has a standard, wherein the case of the tags and filename should always match.