Give form fields an active/inactive state

I'm upgrading an existing d6 site to d7. I came across your module to do the work of creating custom search forms using the custom paths piece. Love it!

My question is...
How can I add an active/inactive state to the input and select fields? Since my form is in the header of every page, I'd like to theme the inactive text with CSS to a grey when not being used.

Thanks for any advice you can give,
Heidi