if (navigator.appVersion.indexOf('Mac',0) != -1) {
 document.writeln('<' + 'link rel="stylesheet" type="text/css" charset="Shift_JIS" href="css/dv_mac.css" title="FONTPROPERTY" /' + '>');
} 
else if (navigator.appVersion.indexOf('Win',0) != -1) {
 document.writeln('<' + 'link rel="stylesheet" type="text/css" charset="Shift_JIS" href="css/dv_win.css" title="FONTPROPERTY" /' + '>');
}