<html>
<head>
<style>
div.neg
{
  margin: 35px auto 95px auto;
  width: 200px;
  height: 200px;
  box-shadow: 0px 0px 15px -20px #808080 inset;
}
</style>
</head>

<body>
<div class="neg"></div>
</body>
</html>