var br_style = "" ;

if (navigator.appName.indexOf ("Microsoft Internet Explorer") == 0) {
    br_style = "ie.css" ;
} else
if (navigator.appName.indexOf ("Netscape") == 0) {
    br_style = "nn.css" ;
}

if (br_style.length > 0) {
    document.write ("<link rel=\"stylesheet\" href=\"css/" + br_style +"\"\>");
}