//向head标签添加link标签functionincludeLinkStyle(url){
var link = document.createElement("link");
link.rel ="stylesheet";
link.type ="text/css";
link.href = url;
document.getElementsByTagName("head")[0].appendChild(link);}//判断客户端functionIsPC(){
var userAgentInfo = navigator.userAgent;var Agents =newArray("Android","iPhone","SymbianOS","Windows Phone","iPad","iPod");var flag =true;for(var v =0; v < Agents.length; v++){
if(userAgentInfo.indexOf(Agents[v])>0){
flag =false;break;}}return flag;}if(/(iPhone|iPad|iPod|iOS|Android)/i.test(navigator.userAgent)){
//移动端设备includeLinkStyle('css/m.css')}else{
//pc端includeLinkStyle('css/pc.css')}
方法二：利用css3的媒体查询，在不同的分辨率下应用不同的css文件
<head><metacharset="UTF-8"><metahttp-equiv="X-UA-Compatible"content="IE=edge"><metaname="x5-orientation"content="portrait"/><metaname="viewport"content="width=device-width,initial-scale=1.0, maximum-scale=1.0, user-scalable=0,viewport-fit=cover"><title></title><linkrel="stylesheet"type="text/css"href="css/pc.css"media="screen and (min-width: 1000px)"><linkrel="stylesheet"type="text/css"href="css/m.css"media="screen and (max-width: 999px)"></head>