How does the PC Web page to the mobile end automatically load the CSS that adapts to the mobile side.

1, through the link tag to judge to join

I've heard of adding media = "handheld" to the link tag, but this doesn't work with either Android or Apple, and it works by trying the following methods.

<link href= "Mobile.css" rel= "stylesheet" type= "text/css" media= "screen and(max-device-width:1080px)" >

2, through the JS to determine whether the browser is a mobile phone or computer, and then add to the CSS link tag can be. Determine if the cell phone method is as follows

function Isphone () {    var useragentinfo = navigator.useragent;     var agentsreg =/(android|iphone| symbianos| Windows phone|ipad|ipod)/i;     var false ;     if (Useragentinfo.match (Agentsreg)) {        true;    }         return Flag;}

If it is a smart machine return True,ps This method for the previous function machine no matter, thank you ~.

Finish!

How does the PC Web page to the mobile end automatically load the CSS that adapts to the mobile side.