The website is live and renders correctly on my Safari mobile: https://www.spacejam.com/1996/

I may have missed something but where are we saying the website should be recreated with 1996 tech or specs? The model is free to use any modern CSS, there is no technical limitations. So yes I genuinely think it is a good generalization test, because it is indeed not in the training set, and yet it is easy an easy task for a human developer.

The point stands. Whether or not the standard is current has no relevance for the ability of the "AI" to produce the requested content. Either it can or can't.