Retina 屏幕分辨率

.icon {
  background-image: url(example.png);
  background-size: 200px 300px;
  height: 300px;
  width: 200px;
}

@media only screen and (-Webkit-min-device-pixel-ratio: 1.5),
only screen and (-moz-min-device-pixel-ratio: 1.5),
only screen and (-o-min-device-pixel-ratio: 3/2),
only screen and (min-device-pixel-ratio: 1.5) {
  .icon {
    background-image: url(example@2x.png);
  }
}

　　

Retina和普通屏

@media only screen and (min-width: 320px) {

  /* Small screen, non-retina */

}

@media
only screen and (-webkit-min-device-pixel-ratio: 2)      and (min-width: 320px),
only screen and (   min--moz-device-pixel-ratio: 2)      and (min-width: 320px),
only screen and (     -o-min-device-pixel-ratio: 2/1)    and (min-width: 320px),
only screen and (        min-device-pixel-ratio: 2)      and (min-width: 320px),
only screen and (                min-resolution: 192dpi) and (min-width: 320px),
only screen and (                min-resolution: 2dppx)  and (min-width: 320px) { 

  /* Small screen, retina, stuff to override above media query */

}

@media only screen and (min-width: 700px) {

  /* Medium screen, non-retina */

}

@media
only screen and (-webkit-min-device-pixel-ratio: 2)      and (min-width: 700px),
only screen and (   min--moz-device-pixel-ratio: 2)      and (min-width: 700px),
only screen and (     -o-min-device-pixel-ratio: 2/1)    and (min-width: 700px),
only screen and (        min-device-pixel-ratio: 2)      and (min-width: 700px),
only screen and (                min-resolution: 192dpi) and (min-width: 700px),
only screen and (                min-resolution: 2dppx)  and (min-width: 700px) { 

  /* Medium screen, retina, stuff to override above media query */

}

@media only screen and (min-width: 1300px) {

  /* Large screen, non-retina */

}

@media
only screen and (-webkit-min-device-pixel-ratio: 2)      and (min-width: 1300px),
only screen and (   min--moz-device-pixel-ratio: 2)      and (min-width: 1300px),
only screen and (     -o-min-device-pixel-ratio: 2/1)    and (min-width: 1300px),
only screen and (        min-device-pixel-ratio: 2)      and (min-width: 1300px),
only screen and (                min-resolution: 192dpi) and (min-width: 1300px),
only screen and (                min-resolution: 2dppx)  and (min-width: 1300px) { 

  /* Large screen, retina, stuff to override above media query */

}

　　

 

/* iPads (landscape) */
		@media screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : landscape) {
			//你的样式放在这里...
		}
		/* iPads (portrait) */
		@media screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : portrait) {
			//你的样式放在这里...
		}
	

　　iPhone 4

@media only screen and (-webkit-min-device-pixel-ratio : 1.5),only screen and (min-device-pixel-ratio : 1.5) {
	/* Styles */
}