Why don't :before and :after pseudo elements work with `img` elements?

Question

I am trying to use a :before pseudo element with an img element.

Consider this HTML and CSS...

HTML

<img src="http://0.gravatar.com/avatar/this-is-not-a-hash" alt="" />

CSS

img:before {
  content: "hello";
}

jsFiddle.

This does not produce the desired effect (tested in Chrome 13 and Firefox 6). However, it works with a div or span element.

Why not?

Is there a way to make pseudo elements work with img elements?

Answer 1

The spec says...

Note. This specification does not fully define the interaction of :before and :after with replaced elements (such as IMG in HTML). This will be defined in more detail in a future specification.

I guess this means they don't work with img elements (for now).

Also see this answer.