[Plugin: Newsletter Sign-Up] Help with CSS

I’d like to style the form like this: http://i.imgur.com/27yFj.jpg
no label, no submit button, just “enter your e-mail and hit enter” text inside the box (similar to the search box).

I have no problem to get the form to the header and it works well. It does submit the entered e-mail address to mail chimp. So no problem with the functionality. I just don’t know how to restyle the form. When I add my style with the background image into my css file, it doesn’t work. It’s still shows up the original form with the label and submit button.

I have this in the header.php file:
<div class=”newsletter”>
<?php if(function_exists(‘nsu_signup_form’)) nsu_signup_form(); ?>
</div><!– end newsletter –>

And then the #newsletter style in my css file, but it does change anything.

Thank you!

http://wordpress.org/extend/plugins/newsletter-sign-up/