[lpapez]

This reminds me of the early Internet in the 90s and 2000s, you had falling snow and star animations everywhere.

This is a Javascript library, but it couldn't have been JS back in those days.

Anyone have an idea how people built stuff like this without JS? I'm curious.

[isp]

JavaScript has been about since 1995, and certainly by no later than the early 2000s was used for these animations.

[Rumudiez]

tiled gifs, most likely