Menu wrapping - Chrome CSS Issue

Have a look at the following page:

http://berrisford.gumpshen.com/

The last item in the top nav menu wraps in chrome I can't pin it down ca开发者_如何学Cn anyone help please?

Change the width of the last LI to 255px and you'll see what i mean.

The last item is too large :)

for ul.topnav change font-size:1.1em to font-size:1em