
(function (doc, win) {
        var docEl = doc.documentElement,
        resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
        recalc = function () {
        var clientWidth = docEl.clientWidth;
        if (!clientWidth) return;
                docEl.style.fontSize = 100 * (clientWidth / 640) + 'px';
        };
        if (!doc.addEventListener) return;
                win.addEventListener(resizeEvt, recalc, false);
                doc.addEventListener('DOMContentLoaded', recalc, false);
})(document, window);
