if(
(navigator.userAgent.match(/iPhone/i) ) || 
(navigator.userAgent.match(/iPad/i) ) || 
(navigator.userAgent.match(/iPod/i) ) || 
(navigator.userAgent.match(/Android/i) ) 
) 
{
    var fileref=document.createElement("link");
    fileref.setAttribute("rel", "stylesheet");
    fileref.setAttribute("type", "text/css");
    fileref.setAttribute("href", "fileadmin/templates/mobil.css");
    document.getElementsByTagName("head")[0].appendChild(fileref);
}