It's just not one based on states, mutability, and variables. Even the things that use the `var` keyword are constants, not variables.
(But then, don't read that as being against scoped rules. The fact that all rules are global to the document is bad. We can emulate scopes with specific selectors, but that's the kind of thing a language is supposed to help with.)
Constants which you can redefine/shadow in scopes, and change the values of at runtime via JS.
They seem like variables to me.
No, you can't. You can set a new value and reevaluate everything.
elem.style.setProperty(‘—var-name’, newValue);
To me, that justifies the name “variable” from the perspective of the CSS.