原始代码：
<html>
<head>
<meta charset="utf-8">
<meta content="ie=edge" http-equiv="x-ua-compatible">
<meta name="viewport" content="width=device-width,initial-scale=1.0,maximum-scale=1.0,user-scalable=0" />
</head>
<style type="text/css">
#content{
width:7.2rem
} .price-div{
background-color:yellow;
} .price-div span{
background-color:green;
} .price-unit{
font-size:0.25rem;
} .price-number{
font-size:0.31rem;
}
</style>
<body>
<div id="content" style="float:left">
<div class="price-div" >
<span class="price-unit">￥</span>
<span class="price-number">42</span>
</div>
</div> <script type="text/javascript">
//计算字体大小
var calculateFontSize = function () {
var BASE_FONT_SIZE = 100; var docEl = document.documentElement,
clientWidth = docEl.clientWidth;
if (!clientWidth) return;
docEl.style.fontSize = BASE_FONT_SIZE * (clientWidth / 720) + 'px'; };
calculateFontSize(); // Abort if browser does not support addEventListener
if (document.addEventListener) {
var resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize';
window.addEventListener(resizeEvt, calculateFontSize, false);
document.addEventListener('DOMContentLoaded', calculateFontSize, false);
} </script>
</body>
</html>
效果：
原因：
rem缩放，导致，去掉缩放的js代码就好了。但这个不是解决办法。
解决方法一：
div设置高度并采用相对定位,span采用绝对定位。
<style type="text/css">
#content{
width:7.2rem
} .price-div{
background-color:yellow;
height:0.4rem;
line-height:0.4rem;
position:relative;
} .price-div span{
background-color:green;
} .price-unit{
font-size:0.25rem;
position:absolute;
top:0rem;
left:0.2rem;
} .price-number{
font-size:0.31rem;
position:absolute;
top:0rem;
left:0.5rem;
}
</style>
效果：
解决方法二：
div设置高度，span等内联元素设置vertical-align为top。
<style type="text/css">
#content{
width:7.2rem
} .price-div{
background-color:yellow;
height:0.4rem;
line-height:0.4rem;
} .price-div span{
background-color:green;
} .price-unit{
font-size:0.25rem;
vertical-align:top;
} .price-number{
font-size:0.31rem;
vertical-align:top;
}
</style>
效果：
