Hi. I'm puzzled.
displays navigation fine in Chrome, Firefox, and Opera, but in IE8, the navigation displays like it would on a mobile device.
It is a Wordpress child theme of TwentyTwelve.
I think the mobile display comes from TwentyTwelve - I have checked plugins and themes, can cannot find anything which is producing this. TwentyTwelve is billed as a responsive theme.
Regardless, the mobile navigation should only display for a screen width of less than 600px.
Can you see why a full-screen IE8 is displaying CSS for screen width of less than 600px?