ua=navigator.userAgent
csstest="<link rel='stylesheet' type='text/css' href='"

if(ua.indexOf("Win")!=-1){

if(document.getElementById && document.all){
document.write(csstest+"win/ie5.css'>")
}
 else if(document.all && !document.getElementById){
document.write(csstest+"win/ie4.css'>")
}
 else if(document.getElementById && !document.all){
document.write(csstest+"win/n6.css'>")
}
 else if(document.layers){
document.write(csstest+"win/n4.css'>")
}
}

if(ua.indexOf("Mac")!=-1){

if(document.getElementById && document.all){
document.write(csstest+"mac/ie5.css'>")
}
 else if(document.all && !document.getElementById){
document.write(csstest+"mac/ie4.css'>")
}
 else if(document.getElementById && !document.all){
document.write(csstest+"mac/n6.css'>")
}
 else if(document.layers){
document.write(csstest+"mac/n4.css'>")
}
}