How to pass parameters to css classes

Question

I want to know is it possible to add some flexibility to css via this:

where .round i

Answer 1

For anyone stumbling across this in 2018, whilst not fully supported CSS variables now give you the ability to pass a variable directly into your class.

You can also define root variables and pass them in as well

This is also scoped to the element as well. If you set the --radius in one element is wont effect another element. Pretty jazzy right!