Love Josh's work and usually always learn something new from his tutorials.

However, this time, I was really hoping the example implementations would use CSS transforms instead of properties that require repaints, especially since the rationale given here for using sprites is performance.

Maybe layer compositing warrants its own article and is beyond the scope here, but you can really tell when whoever built a frontend knows their stuff because all animations are hitting a consistent 60fps.

It's also worth noting that if you're looking to eliminate an additional request, data-urls are a nice way to be fully flicker-free.