Untitled

<head>
<title>Retina Test</title>
<style type="text/css">
#test {background-color:green; height: 20px width: 20px}
@media all and (-webkit-min-device-pixel-ratio: 1.5) {
#test {background-color:blue; height: 20px width: 20px}
   }
</style>
</head>
<body>
<div id="test">test</div>
</body>