function getInternetExplorerVersion() {
    var rv = -1; // Return value assumes failure.
    if (navigator.appName == 'Microsoft Internet Explorer') {
        var ua = navigator.userAgent;
        var re = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
        if (re.exec(ua) != null)
            rv = parseFloat(RegExp.$1);
    }
    return rv;
}
function checkVersion() {
    var msg = "You're not using Windows Internet Explorer.";
    var ver = getInternetExplorerVersion();
    if (ver > -1) {
        if (ver >= 8.0)
            msg = "You're using a recent copy of Windows Internet Explorer."
        else
            msg = "You should upgrade your copy of Windows Internet Explorer.";
    }
        alert(msg);
}

function fondoie8() {
    var ver = getInternetExplorerVersion();
    if (ver == 8.0){        
        if (screen.width<=1280){ 
            document.body.style.backgroundImage='url("images/fondo_bambu_43.jpg")';
        }
    }
}