var ua  = navigator.userAgent.toLowerCase();
var link_css="";

isope=ua.indexOf('opera')!=-1;
ismie=ua.indexOf('msie')!=-1 && ua.indexOf('mac')!=-1;
iswie=ua.indexOf('msie')!=-1 && ua.indexOf('win')!=-1;
isomz=ua.indexOf('gecko')!=-1 ;
ismac=ua.indexOf('mac')!=-1;
iswin=ua.indexOf('win')!=-1;