How can I restyle the Subcribe button on eNewsletter?

I'm using the eNewsletter plugin to provide a call to action on a landing page and I'd like to style the "Subscribe" button to be big, bright, red and generally more eye catching than it is now.

http://wescodothan.com/

Can this be done from within the plugin or do I need to get my hands dirty in the CSS?

Many thanks