rem布局，参考：https://www.jianshu.com/p/86f46ad5b51d
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no" />
<link href="../../css/mui.min.css" rel="stylesheet" />
<script src="../../js/mui.js"></script>
<script src="../../js/vue.js"></script>
<style>
body{max- 750px; min- 320px; margin: 0 auto; background-color: #F5F5F5;overflow-x: hidden;
font-family: -apple-system,Helvetica,sans-serif;}
div{font-size: .26rem; color: #474747;line-height: 2;}
span{font-size: .28rem; color: #D1021F;}
</style>
<script>
(function(doc, win) {
var w = document.documentElement.clientWidth;
if (w > 750) {
w = 750
} else if (w < 320) {
w = 320
}
var f = w / 750 * 100 + "px";
document.documentElement.style.fontSize = f;
var docEl = doc.documentElement,
resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
recalc = function() {
var clientWidth = docEl.clientWidth > 750 ? 750 : docEl.clientWidth;
if (clientWidth > 750) {
clientWidth = 750
} else if (clientWidth < 320) {
clientWidth = 320
}
if (!clientWidth) return;
docEl.style.fontSize = 100 * (clientWidth / 750) + 'px';
};
if (!doc.addEventListener) return;
win.addEventListener(resizeEvt, recalc, false);
doc.addEventListener('DOMContentLoaded', recalc, false);
})(document, window);
</script>
</head>