"The Space Jam website is simple: a single HTML page, absolute positioning for every element, and a tiling starfield GIF background.".
This is not true, the site is built using tables, not positioning at all, CSS wasn't a thing back then...
Here was its one-shot attempt at building the same type of layout (table based) with a screenshot and assets as input: https://i.imgur.com/fhdOLwP.png