I see - I've been checking the PDF output so far, not the DOCX output.
$html .= "
<style type='text/css'>
.tbl-summary { border-collapse:collapse; }
.tbl-summary thead tr th,
.tbl-summary thead tr td,
.tbl-summary tbody tr td
{
border:1px solid #000000;
padding:5px;
text-align:center;
width:100px;
}
.tbl-summary tbody tr td:first-child
{
text-align:left;
}
</style>
";
$html .= "<table class='tbl-summary' style='font-size:12px'>";
$html .= "<thead>
<th width='250'></th>
<th>FY 1</th>
<th>FY 2</th>
<th>FY 3</th>
<th>FY 4</th>
<th>FY 5</th>
</thead>
";
$html .= "<tbody>";