Add CSS to the table created from javascript

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Javascript

var num;
   var uniqueName = new Date();

   var windowName = 'Print' + uniqueName.getTime();
   var printWindow = window.open(num, windowName, 'left=50000,top=50000,width=0,height=0');

   printWindow.document.write("<table id='customers'  border='1' cellpadding='0' cellspacing='0' style='width:80%; border-collapse:collapse;text-align:left'><tr><td><b>Date</b></td><td >8/8/2011</td></tr><tr><td><b>Project</b></td><td>Sample Project</td></tr></table>");
   printWindow.document.close();
   printWindow.focus();
   printWindow.print();
   printWindow.close();

how to apply css class in this case to the table that is created
i want to apply css class to this table
How to do this.

#customers tr.alt td
{
color:#000000;
background-color:#EAF2D3;
}

Please help me.

Thanks in advance