JS判断不同操作系统显示不同样式css

<script type="text/javascript">
        var system ={};  
        var p = navigator.platform;             //判断是否为PC
        system.win = p.indexOf("Win") == 0;  
        system.mac = p.indexOf("Mac") == 0;  
        system.x11 = (p == "X11") || (p.indexOf("Linux") == 0);     
        if(system.win||system.mac||system.xll){

        }
        else{
            function addNewStyle(news) {
            var styleElement = document.getElementById('p1');

            if (!styleElement) {
                styleElement = document.createElement('style');0
                styleElement.type = 'text/css';
                styleElement.id = 'createElement';
                document.getElementsByTagName('head')[0].appendChild(styleElement);
            }
            styleElement.appendChild(document.createTextNode(news));
        }
        addNewStyle('.logos{display:none;}')   //新添加的样式
        addNewStyle('.twom{display:none;}')
         }
        </script>