/*动态改变根元素字体大小*/function recalc() {	var clientWidth = document.documentElement.clientWidth;	if(!clientWidth) return;	document.documentElement.style.fontSize = 20 * (clientWidth / 640) + 'px';}function initRecalc() {	recalc();	var resizeEvt = 'osrientationchange' in window ? 'orientationchange' : 'resize';	if(!document.addEventListener) return;	window.addEventListener(resizeEvt, recalc, false);	document.addEventListener('DOMContentLoaded', recalc, false);}initRecalc();