Never encountered a problem with CSS unless the syntax was incorrect. It is pretty easy to leave off a double-quotation mark, semi-colon, curly bracket, etc. If you do you might get some weird effects. Also, it is pretty easy to get the syntax in the HTML incorrect. I once searched a long time trying to discover why a particular CSS style would not work correctly and finally noticed that I had typed the class name incorrectly into the HTML tag. That is, it was spelled slightly different from what I used in the CSS. You must also be careful with case sensitivity.