(function(doc, win) { var docEl = doc.documentElement, resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize', recalc = function() { var clientWidth = docEl.clientWidth; if (!clientWidth) return; if( clientWidth > 750 ){clientWidth = 750}; docEl.style.fontSize = 100 * (clientWidth / 750) + 'px' }; recalc(); if (!doc.addEventListener) return; win.addEventListener(resizeEvt, recalc, false); // doc.addEventListener('DOMContentLoaded', recalc, false) })(document, window);