Sizing text boxes/buttons

Hi there,

I’m having a real headache trying to shorten the width of my ‘mailing list’ text button at the bottom of the sidebar on http://www.rapnews.co.uk I’d like it to be uniformed with the higher ‘search’ text box and button.

I’ve been tweeking things here and there in my CSS but haven’t had any joy. Sure I’m missing something obvious… Can you help?

Thanks for your time. Tee.