Table header not receiving CSS (I think)

Question

Hi, I have some simple HTML here,

<table class="table shipment" id="payItems">
 <thead>
  <tr>
   <th class="sku">Varekode    </th>
       <th class="productName">Produkt</th>
      <th>Pris</th>
   <th>Antall</th>
   <th style="text-align: right; padding-right: 80px;">Sum</th>

  </tr>
 </thead>
 <tbody>
...content...
 </tbody>
</table>

And this css:

 table#payItems.table thead th
{
 border: 0;
}

Because it's in a wrapper div with rounded corners, and the top th has a top border I want to get rid of, but any combination of th, tr, thead doesn't seem to get rid of this border.

Thanks for any help :)

EDIT: With the insipration from Yi Jiang, I solved it with this:

#payItems thead, #payItems tr { border-top: 0; }

Answer 1

Solved with:

#payItems thead, #payItems tr { border-top: 0; }

Thanks to Yi Jiang for inspiration.