The CSS3 property border-radius lets web designers create boxes with rounded corners without needing the kludge of gifs or pngs with transparent backgrounds.
However, I’ve discovered that not all flavors of MSIE9 are created equal. I’m guessing that the reason the browser on the left does not render the corners is because it sits on a 32-bit version of Windows 7. The browser on the right runs on a 64-bit version of Windows 7. (The hardware is 64-bit in both cases.)
This was having me pull my hair out until I remembered the OS difference. This post is written to help some other poor soul figure out why MSIE 9 is not rendered rounded corners like it’s supposed to!