if ( navigator.platform && ( navigator.platform.indexOf( 'Mac' ) ) > - 1 ) {
    document.write( '<link href="../mac.css" rel="styleSheet" type="text/css">' );
} else {
   if ( navigator.appName.indexOf( 'Microsoft' ) > - 1 ) {
      document.write( '<link href="../win_ie.css" rel="styleSheet" type="text/css">' );
   } else {
     document.write( '<link href="../win_ns.css" rel="styleSheet" type="text/css">' );
   }
}