<style type="text/css">
    td.negative { color : red; }
</style>
<script language="JavaScript" type="text/javascript">
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</script>

<table>
    <tr>
        <td>Column 1</td>
        <td>Column 2</td>
        <td>Column 3</td>
        <td>Column 4</td>
    </tr>
    <tr>
        <td>70.6</td>
        <td>122.4</td>
        <td>-87.1</td>
        <td>99.2</td>
    </tr>
</table>

<script language="JavaScript" type="text/javascript">
  <!--
   MakeNegative();
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</script>