I've written about this technique for capturing HTML elements being created before, it's a pretty cool hack using the animation start event and a uniquely named CSS animation to catch newly created elements being added to the document.
Had a go at some more CSS only animations recently. Turned out kinda cool.
Yet another not-so-new-tech to talk about; CSS keyframe animations. Browser support is just about good enough to use these for things on actual websites now, they've been around for a long time but as usual IE is the sticking point with only version 10 and above offering support.