Need Help in Dynamic CSS generation

[FaRHaN]

I am working on creating Dynamic StyleSheets in wicket, and i found an example 
of similar behaviour in Wicket Examples 
http://cwiki.apache.org/WICKET/dynamically-generate-a-css-stylesheet.html but 
it is not working. When i place the following code in my CSS file (style.css), 
it generates error.
body{background:${color1};}
The css file doesn't recognizes $ simbol. Is this allowed in CSS file or not ? 
Please Help me out to fix this problem.

Thanks
--Farhan--