I think you remembered it wrong. Going from pop-ups was earlier than modals. Pop-ups were supported by things like window.open() which has been around forever (

I think you remembered it wrong. Going from pop-ups was earlier than modals. Pop-ups were supported by things like window.open() which has been around forever (perhaps NetScape 2.0?). In contrast designing a modal requires some slightly more recent CSS like absolute positioning (I believe CSS2 so still within the previous century).