io ho fatto così e funziona benissimo

<html>
<head>
<title>Prova Homepage</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<link href="Foglio_Stile.css" rel="stylesheet" type="text/css">
<body leftmargin="0" topmargin="0">
<table width="1008" height="400" border="0" style{cellspacing: 0px; cellpadding: 0px;}>

<tr bgcolor="red" >
<td> </td>
</tr>
<tr bgcolor="green" border="0" >
<td> </td>
</tr>
</table>
</body>
</html>