highlighting based on mysql result

Hello,
      the code below is working, but I need to highlight based on result that are
unmatched empno,code & amount in different colors.

This code is for finding unmatched columns from 2 tables [employee & emp_det]

$res = mysql_query("SELECT * FROM employee WHERE NOT EXISTS(SELECT 1 FROM emp_det WHERE empno = emp_det.empno AND code = emp_det.code AND amount = emp_det.amount)");

while($row=mysql_fetch_array($res))
{
echo "<tr>";
echo "<td align="center" width="200">" . $row['emp_no']. "</td>";
echo "<td align="left" width="200">" . $row['name'] . "</td>";
echo "<td align="left" width="200">" . $row['dept'] . "</td>";
echo "<td align="center" width="100">" . $row['code'] . "</td>";
echo "<td align="center" width="100">" . $row['amount'] . "</td>";
echo "</tr>";
}

echo "";

need to highlight unmatched values in the 3 columns