In IE9 on Windows 7, I can get it to match your screenshot only when I'm zoomed in at 135%. At 100% it looks perfect. What is the zoom level of IE9 on your machine? (Go to the View menu and choose Zoom). What does it look like at 100%? This is the kind of information that would be very helpful for troubleshooting, so it's a shame that you left it out.
In any case, IE's imperfect zooming algorithm aside, this might be something that the designers consider worthy of being fixed. Consider reporting the issue at the jquery-wp-content repo:
https://github.com/jquery/jquery-wp-content/issues, but please make sure to provide information about zoom level if you do.
--Karl