Some Web designers regard a Web page that validates under both HTML and CSS guidelines as the Holy Grail. I prefer to think of validation as an extremely useful tool, but not a religion. CSS validation, however, is suited perfectly for debugging your code. CSS validators can catch those unclosed curly braces and other typos easily.

Numerous CSS validation services are available. I use the one from the W3C located at http://jigsaw.w3.org/css-validator/.

you can also validate your HTML here: http://validator.w3.org/