rem自适应-针对不同分辨率计算font-size

(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 = 20 * (clientWidth / 320) + 'px';
 };
 if (!doc.addEventListener) return;
 win.addEventListener(resizeEvt, recalc, false);
 doc.addEventListener('DOMContentLoaded', recalc, false);
    })(document, window);

转载自http://www.cnblogs.com/breakdown/p/4231708.html