CSS variables do something fundamentally different than SASS/LESS approaches. Moreover, it is something which those approaches are incapable of doing. Conversely, SASS and LESS do something that CSS can never do - be processed only once.
Much of the confusion I think is in the fact that we are referring to two dramatically different things by the same word "variables". In CSS terms it is more helpful (IMO) to think of them more like "user defined properties" which work exactly like every other property in CSS.
Much of the confusion I think is in the fact that we are referring to two dramatically different things by the same word "variables". In CSS terms it is more helpful (IMO) to think of them more like "user defined properties" which work exactly like every other property in CSS.