Testing which elements can contain pseudo elements
Each browser has a different idea of which elements can contain pseudo-elements or not. This is getting standardized, but if you view this page on different browsers you would notice different elements having the green bars with "PASS" in them.
The summary of the results are in there, if that needs to be amended, fork, update and send me the link on twitter @divya
Original: http://jsfiddle.net/nimbu/GvwVy/
<h1 id="title">Test for elements that have pseudo-elements <b>If you do not see a green bar with the text 'pass' below the element, it means that element cannot have a pseudo-element in the current browser.</b><b>So far<br><br><u>Presto:</u> none on hr.<br><br><u>Webkit:</u> none on img, input.submit, input.button, input.password, input.text, input.search, input.url, input.email, select, option, textarea, progress, meter<br><br><u>Firefox:</u> none on br, input (all types), select, textarea</h1>