menu_browser = "nn3";
menu_mac = false;
if(document.getElementById) menu_browser = "nn6";
if(document.all) menu_browser = "ie";
if(document.layers) menu_browser = "nn";
if(navigator.userAgent.toLowerCase().indexOf("mac")) menu_mac = true;
if(navigator.userAgent.toLowerCase().indexOf("ppc")) menu_mac = true;
if(navigator.userAgent.toLowerCase().indexOf("powerpc")) menu_mac = true;
document.write("<script language=\"JavaScript1.2\" src=\"http://www.opto.com.br/estilos/menu_"+menu_browser+".js\"></script>");