<!DOCTYPE html>
<html>
<head>
    <title>Xem ví dụ</title>
    <style type="text/css">
        div{
            margin:50px;
            width:300px;
            height:200px;
            background-color:#73ad21;
            box-shadow:0px 0px 0px 0px black;
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>