[Plugin: MailChimp List Subscribe Form] How to change input area widths?

Hi, I’m using the this plugin and combining it with the “plugins in page” plugin. As a result the mailchimp plugin is placed nicely within my page, but the width of the input fields are still based on my sidebar widths. How can I adjust this so that the widths are a lot longer to fill more page space? When using firebug, it looks like the actual width of the div area is correct, it’s just the input boxes that are far too narrow.