Web Forms :: List With 1 Or 2, Rows The Row Height Automaticaly Expand To Fill The Height Of The Table?

I have the folllowig css:

div.ListDiv {
width: 750px; /* Table width will be 99% of this */
height: 320px; /* Must be greater than tbody */
overflow: auto;
}
table {
width: 99%; /* 100% of container produces horizontal scroll in Mozilla */
border: none;
}
table>tbody { /* Child selector syntax which IE6 and older do not support */
overflow: auto;
height: 215px;
overflow-x: hidden;
}
thead tr {
position:relative;
top: expression(offsetParent.scrollTop); /* For IE5+ only */
}
thead td {
background-color: #CCCCCC;
font-weight: bold;
}
td {
color: #000000;
text-align: left;
}
table tfoot tr {
position: relative;
overflow-x: hidden;
top: expression(parentNode.parentNode.offsetHeight >= offsetParent.offsetHeight ? 0 - parentNode.parentNode.offsetHeight + offsetParent.offsetHeight + offsetParent.scrollTop : 0);
}
tfoot td {
background-color: #CCCCCC;
}
td:last-child { /* Prevent Mozilla scrollbar from hiding cell content */
padding-right: 20px;
}

When I have a list with 1 or 2, rows the row height automaticaly expand to fill the heigt of the table.

How can I avoid this happening, and have fixed height colimns.