rem适配的代码

    var pixclPatio = 1 / window.devicePixelRatio;
            document.write('<meta name="viewport" content="width=device-width,initial-scale=' + pixclPatio + ',minimum-scale=' + pixclPatio + ',maximum-scale=' + pixclPatio + ',user-scalable=no" />');
            var html = document.getElementsByTagName('html')[0];
            var pageWidth = html.getBoundingClientRect().width;
            html.style.fontSize = pageWidth / 16 + 'px';