移动端rem文字自适式

<script type="text/javascript">
(function (doc, win) {
//  html
var docEl = doc.documentElement,
resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize', recalc = function () {
var clientWidth = docEl.clientWidth;
if (!clientWidth) return;
clientWidth = (clientWidth > 768 ) ? 768 : clientWidth ; docEl.style.fontSize = 10 * (clientWidth / 375 ) + 'px';
};
if (!doc.addEventListener) return; win.addEventListener(resizeEvt, recalc, false);
recalc();
})(document, window);
/*移动端适应大小*/
</script>

.div-1{
width:250px;
height:250px;
background-color: red;
font-size:1.6rem;
}