tablesort alternating rows

tablesort alternating rows

I've seen this question in multiple forms but not many good answers.

In the documentation examples I see the sorted tables have alternating row styles.  When I run table sorter on my tables generated from C#/ASP there are no alternating row styles.  If I put alternating row style in on the server naturally when the table gets sorted the rows no longer alternate since each row maintains its style so the text is randomly light/dark.

How do I turn on alternating row style on on the tablesorter client side.