<!DOCTYPE HTML>
<html lang="en">
<head>
    <title>drop-shadow with negative radius</title>
    <style type="text/css">
        #target {
            width: 100px;
            height: 100px;
            background-color: rgb(0, 255, 0);
        }
    </style>
</head>
<body>
    <div id="target"></div>
</body>
</html>