Is it possible to define a location of an event listed in the calendar and then change the colour of the the cell background accordingly?

eg. events in the main hall appear as red, events in the conference room appear green.

I've got it to change the colour if there is an event but want to change the colour depending on it's location also.

Any help would be great.

 <xsl:choose>
  <xsl:when test="boolean($cell/event)">
  <td class="caleventfound">
  
<xsl:for-each select="$cell/event">
            <a href="{umbraco.library:NiceUrl(@id)}">
                <xsl:value-of select="date:dayinmonth($cell/@date)"/>
    </a>
       </xsl:for-each>
  </td>
</xsl:when>
    
<xsl:otherwise>
  <td>
    <xsl:value-of select="date:dayinmonth($cell/@date)"/>
  </td>
</xsl:otherwise>
</xsl:choose>