1 (function (doc, win) { 2     var docEl = doc.documentElement, 3         resizeEvt = 'onorientationchange' in window ? 'onorientationchange' : 'resize', 4         recalc = function () { 5             var clientWidth = docEl.clientWidth; 6             if (!clientWidth) return; 7             if(clientWidth>=750){ 8                 docEl.style.fontSize = '100px'; 9             }else{10                 docEl.style.fontSize = 100 * (clientWidth / 750) + 'px';11             }12         };13  14     if (!doc.addEventListener) return;15     win.addEventListener(resizeEvt, recalc, false);16     doc.addEventListener('DOMContentLoaded', recalc, false);17 })(document, window);