<!DOCTYPE html>
<html>
<head>
<title>Table border collapse</title>
<style>
table {
border-collapse: collapse;
height: 100px;
width: 100px;
}
td {
background-color: black;
border-radius: 50px;
</style>
</head>
<body>
<table>
<tr>
<td></td>
</tr>
</table>
</body>
</html>