Sorry, Linda...meant to reply to you earlier...
About the only thing you could is possibly change the Selected style so the selected rows are different, but changing the rows themselves...well, that's a bit beyond my CSS ability. Plus, as you've seen, there's no real Class to edit for any row beyond the one that's been selected.
For example, the selected row looks like this:
<tr class="selected" id="ctl00_Split_GP_MPH_hgTickets_0" style="height: 37px;">
The next, unselected row looks like this:
<tr class="alt" id="ctl00_Split_GP_MPH_hgTickets_1" style="height: 37px;">
And the next row, and all subsequent rows after that, look like this:
<tr class="" id="ctl00_Split_GP_MPH_hgTickets_2" style="height: 37px;">
So there's no class you can edit that would impact much of anything except for editing the selected row.