if(navigator.platform == "MacIntel")
{
document.write('<link rel="stylesheet" type="text/css" href="MAC.css">');
}
else if(navigator.platform == "Win32")
{
document.write('<link rel="stylesheet" type="text/css" href="WIN.css">');
}
else
{
document.write('<link rel="stylesheet" type="text/css" href="OTHER.css">');
}