var OSName="UnknownOS";
if (navigator.appVersion.indexOf("Win")!=-1) OSName="Windows";
if (navigator.appVersion.indexOf("Mac")!=-1) OSName="MacOS";
if (navigator.appVersion.indexOf("X11")!=-1) OSName="UNIX";
if (navigator.appVersion.indexOf("Linux")!=-1) OSName="Linux";
if(OSName=="Windows")
   document.write("<link rel='stylesheet' href='js/winstyle.css' type='text/css'>")
   else 
   document.write("<link rel='stylesheet' href='js/macstyle.css' type='text/css'>" )