Title bar stretched in IE (only IE)

After using the monochrome theme for the past month, I only noticed recently that something’s up with the site in Internet Explorer 8. I usually test in both Chrome and Firefox, but perhaps freudianly forgot to test in IE (which like most people I avoid like the plague whenever I can).

here’s the site: http://entitygreen.com

As you can see in IE, it expands the title bar out over the entire width of the page, a problem which does not appear in any other tested browser.

I’d normally try to troubleshoot this myself, but because I haven’t changed anything recently to ‘roll back’ on here, I’m at a loss for what I could have done…I’m definitely not too good with HTML theme troubleshooting yet!

Any thoughts?