Ah, that makes total sense. And yeah I've been using :before and :after ever since they became a part of CSS (even before they were widely-supported), so seeing the :: versions caught me by surprise.
Anyway, thanks for the clarification! It all makes sense in retrospect, although it still seems weird to me that they decided that there needs to be specific syntax for pseudo-elements vs. pseudo-classes. It doesn't seem likely that they'd ever allow the two to collide, for example...
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