New Post: Rowspan is not working as expected

I have a table in html page which has many rowspan , colspan in it. The table structure is give below:

<table align="center" border="1">
    <tbody>
        <tr>
            <td align="center" style="background-color: rgb(135,206,235);" colspan="2"><strong><span style="font-size: 13px; font-family: tahoma;">Change Type</span></strong></td>
            <td align="center" style="background-color: rgb(135,206,235);"><strong><span style="font-size: 13px; font-family: tahoma;">Change Risk</span></strong></td>
            <td align="center" style="background-color: rgb(135,206,235);"><strong><span style="font-size: 13px; font-family: tahoma;">Approval Body</span></strong></td>
        </tr>
        <tr>
            <td rowspan="4"><strong><span style="font-size: 13px; font-family: tahoma;">Emergency</span></strong></td>
            <td rowspan="4"><strong><span style="font-size: 13px; font-family: tahoma;">Normal</span></strong></td>
            <td align="center" style="background-color: rgb(255,0,0);"><strong><span style="font-size: 13px; font-family: tahoma;">Level 1</span></strong></td>
            <td align="center"><span style="font-size: 13px; font-family: tahoma;">MS COO</span></td>
        </tr>
        <tr>
            <td align="center" style="background-color: rgb(255,165,0);"><strong><span style="font-size: 13px; font-family: tahoma;">Level 2</span></strong></td>
            <td align="center"><span style="font-size: 13px; font-family: tahoma;">CAB or E-CAB</span></td>
        </tr>
        <tr>
            <td align="center" style="background-color: rgb(255,215,0);"><strong><span style="font-size: 13px; font-family: tahoma;">Level 3</span></strong></td>
            <td align="center"><span style="font-size: 13px; font-family: tahoma;">CAB or E-CAB</span></td>
        </tr>
        <tr>
            <td align="center" style="background-color: rgb(255,255,0);" rowspan="2"><strong><span style="font-size: 13px; font-family: tahoma;">Level 4</span></strong></td>
            <td align="center"><span style="font-size: 13px; font-family: tahoma;">Originator's Manager</span></td>
        </tr>
        <tr>
            <td align="center" colspan="2"><strong><span style="font-size: 13px; font-family: tahoma;">Standard</span></strong></td>
            <td align="center"><span style="font-size: 13px; font-family: tahoma;">Originator's Manager</span></td>
        </tr>
    </tbody>
</table>

When I am trying to convert this html code into Open xml , the table structure is totally messed up. On top of that the color from previous cell is overflowing to next cell.

Can you please help me on fixing it.
I am using htmltoopenxml 1.4 version.