[Shelley_c]

At the bottom of each styles main css you have the option to add replacement variables.

At the very bottom of your "all style options" page for each style (where you input the css values, etc) you'll see a box titled "Replacements Variables". Click "Add new replacement variable", select the style you want different images to show in. In the Search for Text box type in the original url, eg /images/icons/originalformat.gif and in the Replace with Text box type in the new url to the images, for example /newstyle/images/icons/whateverformat.png