[Koha] Changing the blue color on the search bar of OPAC

Hi all, I have managed to change the background color for my koha OPAC. Now I want to change the blue background color on the search bar to suit my corporate colors. Any idea on how to achieve this? Alternatively, which tag should I change in the opac.css file to achieve this? Kind Regards, Admire Mutsikiwa University of Zimbabwe