Below is the rendered markup:

South Park Al
Light Row Here
Dark Row Here

Problem

Bugs in the following browsers:

Solution (partial to IE7 only)

With tr.headrow having "position:relative" and td/th having "background-image:none"

South Park Al
Light Row Here
Dark Row Here

The above workaround only works for IE7. More info via this post.

Or using "expression"… More info via this post.

South Park Al
Light Row Here
Dark Row Here

Note: The above workaround seems to weird effect on the y-position of the image in IE7.

There is also a thread at Snook's site here (same partial solution as the first)