LESS is a  dynamic style-sheet language.

It extends CSS with dynamic behavior such as  variables, mixins,  operations  and  functions. LESS runs on both the client-side (Chrome, Safari, Firefox) and server-side. I prefer to compile it using the  simpLESS compiler for Windows 7. This takes my LESS code and generates the CSS files on the fly.

Find out more about LESS or SimpLESS . What’s even better is that they are both free!