I don't get why this is "awesome".<p>CSS for icons is like HTML tables for markup. You have a path, split it to pieces you can represent with CSS using the methods you consider acceptable and draw a shape using ::before and ::after pseudo-elements.<p>Sure, those icons were carefully hand-crafted. This requires a lot of patient work, and this is admirable.<p>Yet, we have SVG for vector graphics. Embed it with data: URIs (I believe browsers who support CSS3 transforms can display SVG backgrounds) and that's it.