(function() {

        var psdWidth = 1080,

            maxRem = 100,

            ch = document.documentElement.clientHeight || document.body.clientHeight,

            cw = document.documentElement.clientWidth || document.body.clientWidth,

            pageWidth;

        var calcRem = function() {

            if (window.orientation && (window.orientation == 90 || window.orientation == -90)) {

                pageWidth = Math.max(ch, cw);

            } else {

                pageWidth = Math.min(ch, cw);

            }

            var rem = (pageWidth / psdWidth * 100).toFixed(2);

            rem = Math.min(rem, maxRem);

            window.rem = rem;

            document.getElementsByTagName('html')[0].style.fontSize = rem + 'px';

        };

        calcRem();

        window["onorientationchange" in window ? "onorientationchange" : "onresize"] = calcRem;

    })();