<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script>
;(function(doc,win,undefined){
const docEl = doc.documentElement;
const resizeEvt = 'orientationchange' in win? 'orientationchange' : 'resize';
const recalc = function () {
const clientWidth = docEl.clientWidth;
if(clientWidth === undefined) return;
docEl.style.fontSize = 20 * (clientWidth / 320) + 'px';;
};
if(doc.addEventListener === undefined) return;
win.addEventListener(resizeEvt, recalc, false);
doc.addEventListener('DOMContentLoaded', recalc, false);
}
)(document, window);
</script>
<style>
*{
padding: 0;
margin: 0;
}
html{ font-size: 62.5%;}
body{ font-size: 16px;}
.box{
100%;
background: red;
height: 1rem;
}
.inner{
13rem;
height: 1rem;
background-color: blue;
}
/* 设计图尺寸/85.375
* 85.375来源为 标准尺寸下的html font-size为16px ，但是经过计算后的font-size为85.375。故此值为这样来的。
*/
.asdfasdf{
font-size: .2rem;
}
</style>
</head>
<body>
<div class="box">
<div class="inner">
<div class="asdfasdf">
a
</div>
</div>
</div>
</body>
</html>