HTML Writer missing styles if rowspan/colspan

[fglueck]

I'm using phpexcel 1.7.9 and have a new problem with the HTMLWriter.
A Cell have no styles when they have a rowspan or a colspan:

<thead>
          <tr style="">
            <td rowspan="3" style="">Element <br><<<<----- here
(Anzahl Gruppen <br>
/ Productcodes)</td>
            <td colspan="2" style="">Eingang</td><<<<----- here
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">Eing.</td>
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">Best.</td>
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">Best.</td>
          </tr>
          <tr style="">
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">Schnitt</td>
            <td rowspan="2" style="">Anteil <br> <<<<----- here
(Ebene)</td>
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">34</td>
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">34</td>
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">34</td>
          </tr>
          <tr style="">
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">20.05.<br>
-25.08.</td>
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">19.08.<br>
-25.08.</td>
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">25.08.</td>
            <td style="vertical-align:top; text-align:center; border-bottom:2px solid #f5f5f5; border-top:2px solid #f5f5f5; border-left:2px solid #f5f5f5; border-right:2px solid #f5f5f5; font-weight:bold;   background-color:#dae4e5; ">Anteil</td>
          </tr>
        </thead>

Normaly they have all the same style.
There is no problem with ExcelWriter for xls or xlsx.
Greetings
Frank