Even though Internet Explorer (IE) is the most compatible browser with websites, it is not very compliant with web standards. Acid2 is one test of how modern browsers work with some specific features across several different web standards. IE7 does not show the Acid2 face properly…show doesn’t Firefox 2.0. Weird ha? However Firefox 3.0 (beta) does, and Opera 9 also does. The upcoming IE8 browser will also render the face properly.

This is how the rendered image looks like on IE8.

ACID2 face on IE8

Read more about this here.