@viewport

Summary

The @viewport CSS at-rule contains a set of nested descriptors in a CSS block that is delimited by curly braces. These descriptors control viewport settings, primarily on mobile devices.

Syntax

(This MDN article is currently a stub and lacks a full description of the syntax.)

@viewport {
  /* viewport-descriptor: viewport-value; */ 
}

A zoom factor of 1.0 or 100% corresponds to no zooming. Larger values zoom in. Smaller values zoom out.

Descriptors

Browsers are supposed to ignore unrecognized descriptors.

min-width: Used in the determination of the width of the viewport when the document is first displayed.
max-width: Used in the determination of the width of the viewport when the document is first displayed.
width: A shorthand descriptor for setting both min-width and max-width
min-height: Used in the determination of the height of the viewport when the document is first displayed.
max-height: Used in the determination of the height of the viewport when the document is first displayed.
height: A shorthand descriptor for setting both min-height and max-height
zoom: Sets the initial zoom factor.
min-zoom: Sets the minimum zoom factor.
max-zoom: Sets the maximum zoom factor.
user-zoom: Controls whether or not the user should be able to change the zoom factor.
orientation: Control's the document's orientation.

Examples

@viewport {
  min-width: 640px;
  max-width: 800px;
}
@viewport {
  zoom: 0.75;
  min-zoom: 0.5;
  max-zoom: 0.9;
}
@viewport {
  orientation: landscape;
}

Specifications

Specification	Status	Comment
CSS Device Adaptation The definition of '@viewport' in that specification.	Working Draft

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	29 (behind a flag)	Not supported	10 -ms	11.10 Removed in 15 Reintroduced behind a flag in 16	Not supported

Feature	Android	Chrome for Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
Basic support	4.4	29	Not supported	10-ms[1]	11.10 Removed in 15 Reintroduced behind a flag in 16	Not supported

[1] There is a bug in IE Mobile 10 on older versions of Windows Phone 8, where device-width, when used within @-ms-viewport, evaluates to the screen width in physical pixels rather than normalized CSS pixels, which is wrong according to the specification. However, when used within a viewport <meta> tag, device-width evaluates correctly. According to Microsoft, this bug was fixed in Windows Phone 8 Update 3 (a.k.a. GDR3), although there are some reports that the Lumia Black GDR3 update did not fix the bug (at least on the Lumia 920). For more details and a workaround, see Tim Kadlec's blog post "Windows Phone 8 and Device-Width".