<!--页面编码规则-->
<meta charset="UTF-8" />
<!--设置浏览器以文档最高模式启用-->
<meta http-equiv="X-UA-Compatible" content="IE-edge,chrome=1" />
<!--设置适应移动设备-->
<meta name="viewport" content="width=device-width; initial-scale=1.0">

<!--判断是否IE9一下-->
<!--[if lt IE 9]>
<script type="text/javascript" src="js/css3-mediaqueries.js"></script>
<![endif]-->
<!--[if lt IE 9]>
<script type="text/javascript" src="js/html5.js"></script>
<![endif]-->

<!--外联样式（响应式布局）-->
<link href="css/响应式布局Two-490.css" rel="stylesheet" type="text/css" media="screen and (max-width:490px)" />
<link href="css/响应式布局Two-980.css" rel="stylesheet" type="text/css" media="screen and (min-width:490px)"/>

<!--style里的写法-->

<style>

@media screen and (min-width:650px)
{
.div-mess
{
font-size: 20px;
color: Blue;
}
}
@media screen and (max-width:650px)
{
.div-mess
{
font-size: 16px;
color: Orange;
}
}

</style>