body{color:#000;background:#CCC;}
table{border-collapse:collapse;}
td{border:1px solid #000; width:50px; height:50px;}
tr:first-child td:first-child{border-color:#FFF;}
</style>
</head>
<body>
<table><tr><td>1</td><td>2</td></tr><tr><td>3</td><td>4</td></tr></table>
</body>
</html>