rounded corners question - header - iblog4

[jingram 1]

Ok, I did a lot of searching and a lot of trying of custom CSS and haven't made any real progress on this. I'm trying to get the corners to round on the header image. I want this to be controlled via CSS instead of rounding the image itself so IE8 and previous render the same, while firefox, IE9, etc. render with the rounded corners. Any help would be most appreciated. Site in question: www.expeditionkayaking.org