[dech]

Создайте раздел для стилей и затем используйте его:

    <Styles>
      <Style ss:ID="s43">
        <Alignment ss:Horizontal="Center" ss:Vertical="Center" ss:WrapText="1"/>
        <Borders>
          <Border ss:Position="Bottom" ss:LineStyle="Continuous" ss:Weight="1"
           ss:Color="#000000"/>
          <Border ss:Position="Left" ss:LineStyle="Continuous" ss:Weight="1"
           ss:Color="#000000"/>
          <Border ss:Position="Right" ss:LineStyle="Continuous" ss:Weight="1"
           ss:Color="#000000"/>
          <Border ss:Position="Top" ss:LineStyle="Continuous" ss:Weight="1"
           ss:Color="#000000"/>
        </Borders>
        <Font ss:Bold="1"/>
        <Interior ss:Color="#FFFF99" ss:Pattern="Solid"/>
      </Style>
    </Styles>

  <xsl:template match="*" mode ="Header">
    <Cell ss:StyleID="s43">
      <Data ss:Type="String">
        <xsl:value-of select="."/>
      </Data>
    </Cell>
  </xsl:template>