Space CaCSS - Animated CSS3 background patterns. The challenge was to create some trippy effects with just a single <div> element and no extra markup.
How does it work? The basic technique is to use a CSS3 repeating-radial-gradient as a background and animate it by changing its background-size. That’s all what’s needed in the second example. Pretty hypnotic. If you want more variations you can use a second gradient with a different background-size. Or add a second animation for the background-position with a different timing. That makes it possible to create a somewhat random looking motion like in the last example (orange).
You could also add some extra markup and use transforms like rotate, scale or so to make even more trippy effects, but for now I just kept it to background-size and position.
Something to keep in mind: Animating the whole background of a page is not that great of an idea. First it would be waaaay too distracting, then CPU usage is quite high especially if it’s a large area and using Canvas would probably be a better option. Also it doesn’t work in all browsers. But considering how little code is needed (most is just vendor prefixes) to create those animated patterns, it’s super fun to play with.