bootstarp引入的必要操作

utf-8编码

<mata charset="utf-8">

兼容IE浏览器

<meta http-equiv="X-UA-Compatible" content="IE=edge">

兼容IE 9 以下版本的插件

HTML5:

<script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/htnl5shiv.js"></script>

CSS 3样式：

<script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/respond.min.js"></script> 

媒体查询：

<meta name="viewport" content="width=device-width,initial-scale=1">