leatherbarrow on "[Plugin: Contact Form 7] Style File Upload Button and Field"

Hi guys,
I am trying to style the ugly default file upload button and text field. I just can't seem to find the right class to do so. I've heard of a solution using opacity but the problem there is the user can't see the file has been added in the text field. Any help would be greatly appreciated.

http://wordpress.org/extend/plugins/contact-form-7/