Use custom properties to handle components' variants

[ffoodd]

By using custom properties, we may ease contextual variants for components. An example: sizing a component in em would be muc, much easier with things like font-size: calc( 1em * var(--size) );. We should also keep in mind currentColor and inherit values!

And it'll ease theming too :)

[ffoodd]

Some good read on Jonathan Harrell's blog.