This allows you to call specific stylesheets for WebKit browsers (Chrome, Safari...) and Opera

<!--[if !IE]><!-->
    <link rel="stylesheet" href="css/webkit.css" media="screen and (-webkit-min-device-pixel-ratio: 0)" />

    <!-- Legacy : this worked until version 12 -->
    <link rel="stylesheet" href="css/opera.css" media="not screen and (1)" />

    <!-- This shouldn't be needed anyway since Opera is going to use WebKit as well -->
    <script>
        if (window.opera)
            document.write('<link rel="stylesheet" href="css/opera.css" />');
    </script>
<!--<![endif]-->