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The <resolution> CSS data type, used for describing resolutions in media queries, denotes the pixel density of an output device, i.e., its resolution.

On screens, the units are related to CSS inches, centimeters, or pixels, not physical values.

Syntax

The <resolution> data type consists of a strictly positive <number> followed by one of the units listed below. As with all CSS dimensions, there is no space between the unit literal and the number.

Units

dpi
Represents the number of dots per inch. Screens typically contains 72 or 96 dots per inch, but the dpi for printed documents is usually much greater. As 1 inch is 2.54 cm, 1dpi ≈ 0.39dpcm.
dpcm
Represents the number of dots per centimeter. As 1 inch is 2.54 cm, 1dpcm ≈ 2.54dpi.
dppx
Represents the number of dots per px unit. Due to the 1:96 fixed ratio of CSS in to CSS px, 1dppx is equivalent to 96dpi, which corresponds to the default resolution of images displayed in CSS as defined by image-resolution.
x
Alias for dppx.

Note: Although the number 0 is always the same regardless of unit, the unit may not be omitted. In other words, 0 is invalid and does not represent 0dpi, 0dpcm, or 0dppx.

Examples

Use in a media query

@media print and (min-resolution: 300dpi) { ... }

Valid resolutions

96dpi
50.82dpcm
3dppx

Invalid resolutions

72 dpi     Spaces are not allowed between the number and the unit.
ten dpi    The number must use digits only.
0          The unit is required.

Specifications

Specification Status Comment
CSS Values and Units Module Level 4
The definition of '<resolution>' in that specification.
Editor's Draft Adds the x unit.
CSS Values and Units Module Level 3
The definition of '<resolution>' in that specification.
Candidate Recommendation Adds the dppx unit.
Media Queries
The definition of '<resolution>' in that specification.
Recommendation Initial definition.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support29123.599.5 Yes
dppx units291216 No12.1

Yes1

No2

x units ? ?62 ? ? ?
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support No ?12 Yes Yes Yes ?
dppx units ? ?121612.1

Yes1

No2

?
x units ? ? ?62 ? ? ?

1. Supported as device-pixel-ratio.

2. See bug 16832.

See also

文档标签和贡献者

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