LESS extends CSS with the use of dynamic "variables, mixins, operations, and functions".
Variables allow you to define widely used values in a single place. Then you are able to re-use them throughout the style sheet. Making global changes then becomes as easy as changing one line of code.
Mixins allow you take all of the properties of one class and simply include them as the class name in another class. It’s just like variables, but for whole classes.
Operations let you add, subtract, divide and multiply property values and colors, giving you the power to create complex relationships between properties.
The default variables (or constants):
To over-ride the default LESS constants you can use the filter pless_vars