1.Phone4
<link rel="stylesheet" media="only screen and (-webkit-min-device-pixel-ratio: 2)"
type="text/css" href="iphone4.css" />
2.iPad
<link rel="stylesheet" media="all and (orientation:portrait)" href="portrait.css"
type="text/css" />
<link rel="stylesheet" media="all and (orientation:landscape)" href="landscape.css"
type="text/css" />
3.android
/*240px的宽度*/
<link rel="stylesheet" media="only screen and (max-device-240px)"
href="android240.css" type="text/css" />
/*360px的宽度*/
<link rel="stylesheet" media="only screen and (min-device-241px) and (max-device-360px)" href="android360.css" type="text/css" />
/*480px的宽度*/
<link rel="stylesheet" media="only screen and (min-device-361px) and (max-device-480px)" href="android480.css" type="text/css" />