Hola
En el ejemplo de adjunto si está position: fixed; hace caso omiso de
border-bottom-style: none;
SIn embargo si quito
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<style>
table
{
background-color: White;
border-color: #000000;
border-style: solid;
border-width: 1px 1px 0px 0px;
}
table td
{
border-style: solid;
padding: 0 0.5em;
border-width: 0px 0px 1px 1px;
border-color: #000000;
}
table td:first-child
{
/*nbsp;fixed;*/
border-width: 0 1px 1px 1px !important;
width: 20px;
}
table td:first-child + td
{
padding-left: 45px;
}
</style>
</head>
<body>
<div style="overflow: auto; width: 70px;">
<table border='0' cellpadding='0' cellspacing='0'>
<tr>
<td style="position: fixed; border-bottom-style: none;
background-color: White;">
a
</td>
<td>
b
</td>
<td>
3
</td>
<td>
3
</td>
<td>
3
</td>
</tr>
<tr>
<td style="border-bottom-style: none; position: fixed;
background-color: White;">
aa
</td>
<td>
d
</td>
<td>
3
</td>
<td>
3
</td>
<td>
3
</td>
</tr>
<tr>
<td style="border-bottom-style: none; position: fixed;
background-color: White;">
a
</td>
<td>
b
</td>
<td>
3
</td>
<td>
3
</td>
<td>
3
</td>
</tr>
<tr>
<td style="border-bottom-style: none; position: fixed;
background-color: White;">
c
</td>
<td>
d
</td>
<td>
3
</td>
<td>
3
</td>
<td>
3
</td>
</tr>
</table>
</div>
</body>
</html>
