前言：
本文来自于对 http://bjango.com/articles/min-device-pixel-ratio/ 的部分整理：
正文：
- -webkit-min-device-pixel-ratio为1.0
- 所有非Retina的Mac
- 所有非Retina的iOS设备
- Acer Iconia A500
- Samsung Galaxy Tab 10.1
- Samsung Galaxy S
- -webkit-min-device-pixel-ratio为1.3
- Google Nexus 7
- -webkit-min-device-pixel-ratio为1.5
- Google Nexus S
- Samsung Galaxy S II
- HTC Desire
- HTC Desire HD
- HTC Incredible S
- HTC Velocity
- HTC Sensation
- -webkit-min-device-pixel-ratio为2.0
- iPhone 4
- iPhone 4S
- iPhone 5
- iPad (3rd generation)
- iPad 4
- 所有Retina displays 的MAC
- Google Galaxy Nexus
- Google Nexus 4
- Google Nexus 10
- Samsung Galaxy S III
- Samsung Galaxy Note II
- Sony Xperia S
- HTC One X
.search{background:url(img/guide-search.jpg) no-repeat; height:415px;}
.attention{background:url(img/guide-attention.jpg) no-repeat; height:250px;}
.forward{background:url(img/guide-forward.jpg) no-repeat; height:486px;}
/* 高清图 */
@media only screen and (-webkit-min-device-pixel-ratio:2){
.search{background:url(img/guide-search-2x.jpg) no-repeat;background-size:100%;}
.attention{background:url(img/guide-attention-2x.jpg) no-repeat;background-size:100%;}
.forward{background:url(img/guide-forward-2x.jpg) no-repeat;background-size:100%;}
}