xsl:if statement with numeric

hello 
I'm very new to this. 
I have an xml returned that looks like this: 

<td>100</td>
<td>98.00</td>
<td>100</td>

now I'd like to give the td tags different colors, depending on the value.
What I did so far ist that: 

<xsl:template match="monat">
        <xsl:if test= "numeric(.) &lt; 100.00">     
            <xsl:variable name="farbe">#00ff00</xsl:variable>
        </xsl:if>
    <td bgcolor="$farbe" align="right">
        <xsl:apply-templates/>
    </td>
</xsl:template>

My problem is, I think he doesn't make a difference with the value, all
columns get the same color. 
What have I done wrong here?
Thanks for any answers.

-- 
+++ NEU bei GMX und erstmalig in Deutschland: T\V-gepr|fter Virenschutz +++
100% Virenerkennung nach Wildlist. Infos: http://www.gmx.net/virenschutz