That page (and a number of other places) uses <tr class="highlight"> on alternate rows. A number of other places in the pm code explicitly set the background color as $$THEME{clr_highlight} || (some default) where (some default) has various values. It would be a nice project for some pmdevil to go through and standardize everything to use the clr_highlight color (and go through all the standard themes and make sure it's set appropriately).
But, conceptually, if there's no theme set, should we continue to set class="highlight" ?