响应式布局—设备像素密度(-webkit-min-device-pixel-ratio)

常见值对照表：

-webkit-min-device-pixel-ratio: 1.0

All non-Retina Macs
Apple iPhone (1st generation)
Apple iPhone 3G
Apple iPhone 3GS
Apple iPad (1st generation)
Apple iPad 2
Apple iPad mini (1st generation)
Acer Iconia A500
Samsung Galaxy Tab 10.1
Samsung Galaxy S

-webkit-min-device-pixel-ratio: 1.3

Asus MemoPad HD 7
Google Nexus 7 (2012 model)

-webkit-min-device-pixel-ratio: 1.4

Nokia Lumia 520

-webkit-min-device-pixel-ratio: 1.5

Google Nexus S
HTC Desire
HTC Desire HD
HTC Incredible S
HTC Velocity
HTC Sensation
Kindle Fire HD
Samsung Galaxy S II
Sony Xperia Tablet Z
Sony Xperia U

-webkit-min-device-pixel-ratio: 2.0

All Macs with Retina displays
Apple iPhone 4
Apple iPhone 4S
Apple iPhone 5
Apple iPhone 5c
Apple iPhone 5s
Apple iPhone 6
Apple iPhone 6s
Apple iPhone 7
Apple iPad (3rd generation)
Apple iPad 4
Apple iPad Air
Apple iPad mini (2rd generation)
HTC One X
Google Galaxy Nexus
Google Nexus 4
Google Nexus 7 (2013 model)
Google Nexus 10
Motorola Moto X
Samsung Galaxy S III
Samsung Galaxy Note II
Sony Xperia S
Sony Xperia T

-webkit-min-device-pixel-ratio: 2.6

Nokia Lumia 930
Google Nexus 5X

-webkit-min-device-pixel-ratio: 3.0

HTC One (M7)
HTC Butterfly
Huawei Honor 6
Huawei Mate 9
Apple iPhone 6 Plus
Apple iPhone 6s Plus
Apple iPhone 7 Plus
LG G2
Nexus 5
Nexus 6
Motorola Moto G4
OnePlus One
Oppo Find 7 (X9076)
Samsung Galaxy S4
Samsung Galaxy Note 3
Samsung Galaxy Note 4
Sony Xperia Z
Xiaomi Mi 3