Alternate Background Color in List in Joomla Module

We are using the JA_Bulletin Module on our website. We would like the background colors to alternate between white and grey to add contrast to the different articles. (see attached word document for screenshot) The module has the ability to be anywhere from 2 - 20 articles long, so the alternating must be able to handle this as well. Steps required to be considered complete: - Alternate shades to white/light grey no matter how many articles are selected - Preferred to be handled by CSS - All changes to be documented with original and new files supplied. - Subject to testing verification. Demo site can be see @ [login to view URL] The Module is called "Most Read" in the top left portion of the main content area of the site (see attached word document for screenshot.