Can't seem to animate pseudo elements with -webkit-transition. The fiddle below shows what I mean when run in Chrome/Safari, I guess this isn't supported right now?
Fixed in Google Chrome on January 3rd, 2013.
By now (I do update this list) it's supported in:
- FireFox 4.0 and above
- Chrome 26 and above
- IE 10 and above
Waiting for Safari and Chrome for Android to pull these updates.
You can test it yourself in your browser, or
See the browser support table.
Well, actually, you can.
You just need to leverage the often forgotten inherit value.
Unfortunately we can't (yet) directly target pseudo-elements with custom animations, but we surely can let them share the same animation of the "parent" element by inheriting the properties we wish to animate.
See my fiddle here.
来源：https://stackoverflow.com/questions/9798010/css-transitions-with-before-and-after-pseudo-elements