It's not a library or an effect. Have you ever wondered how to make an mp4 file with a transparent background and paint it through the blend mode? Because if you have, this technique will be useful to you. This is a kind of emulation of WebGL spheres.
This is a simple but neat technique to remove the background from a black and white video and color it using the mix-blend-mode property using pure CSS. This technique allows you to emulate various looped and dynamic spheres and shapes without using WebGL with a pre-prepared video.