Less (Leaner Style Sheets; sometimes stylized asLESS) is a dynamic preprocessor style sheet language that can be compiled into Cascading Style Sheets (CSS) and run on the client side or server side.
http://lesscss.org/
The global theme for an application is of this type as well as the dynamic style inclusion available on Behaviour tab of a custom coach view uses these files. In these files you have defined variables and functions to manipulate colors etc.