Linking form ID’s with CSS

Hi there, I’ve been trying and failing all weekend to do a simple formatting alteration to a new text field/button I’ve added to the bottom of http://www.rapnews.co.uk

I didn’t design the site so I’m a novice, but have tried copying the method that appears to make my search box/button the correct colour/theme.

In my sidebar, I’ve called up mailinglist.php which includes the text field and button for people to subscribe to my mailing list.

In this php, the form/button is id’d as mailinglist, and in the style sheet, i’ve copied and pasted the search’s theme colours, and changed the id to mailing list,

but the mailing list box/field still appears white instead of brown….

i know i must be missing something really simple, which is making it even more painful. any ideas please?

thanks.