Theme: DepoMasthead IE centering issue

Hey all,

I’ve customized my version of DepoMasthead with a few TypeKit changes and some custom CSS. Seems to be working smoothly on Firefox, Chrome and Safari, but on IE the boxes aren’t extending to full length, and the search button down the bottom isn’t centering.

Here’s my blog: https://darkmooninorbit.wordpress.com

Here’s the CSS:

[no need to post CSS – it’s all visible on your site and you also MUST use the code buttons when posting any code on these forums]

Any suggestions? I checked the DTD via a validator and no errors came up for *that* (others, yes, but they seem to be theme or WordPress default), so IE shouldn’t be kicking over into quirks mode.