html5对分辨率和设备的嗅探方法

参考地址：

http://pugetworks.com/2011/04/css-media-queries-for-targeting-different-mobile-devices/

http://blog.sina.com.cn/s/blog_83940dfb0100yrfm.html

http://developer.android.com/guide/webapps/targeting.html

http://www.fiveminutes.eu/targeting-hight-screen-densities-with-css-media-queries/