<!DOCTYPE html>
<html><head><title></title>
<style>
body { margin:0; padding:0; }
#glass {
opacity:0.4;
background-color:white;
position:absolute;
top:0px; left:0px; right:50px; bottom: 50px;
}
</style>
</head>
<body>
<div id="glass"></div>
</body>
</script>
</html>