To write separate CSS for mac os ,Copy the below script into the head tag of your page   <script type="text/javascript">   var csstype="inline" //Specify type of CSS to use. "Inline" or "external"   var mac_css='body{font-size: 14pt; }' //if "inline", specify mac css here  var pc_css='body{font-size: 12pt; }' //if "inline", specify PC/default css here   var mac_externalcss='/style/macstyle.css' //if "external", specify Mac css file here  var pc_externalcss='/style/pcstyle.css'   //if "external", specify PC/default css file here   ///////No need to edit beyond here////////////   var mactest=navigator.userAgent.indexOf("Mac")!=-1  if (csstype=="inline"){  document.write('<style type="text/css">')  if (mactest)  document.write(mac_css)  else  document.write(pc_css)  document.write('</style>')  }  else if (csstype==...