Error: The frameborder attribute on the iframe element is obsolete

Hi,
I just came across this error when validating html:

Error: The frameborder attribute on the iframe element is obsolete. Use CSS instead.

>From line 10, column 6; to line 10, column 96

er">↩ <iframe id="headerFrame" src="pages/header.html" title="Header navigation" frameBorder="0">↩ 


This html needs to work in IE8. I could not find a way to remove the frame borders in IE8 in CSS. When I apply border: 0 or frameborder: 0 to iframe in css or even to the id of an iframe in css, it does not remove the frameborder in IE8.

Cheers,
Ben