Conditional rules

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CSS Conditional Rules specification.

The conditional rules module is mostly about the syntax for at-rules such as media queries, @font-face, and the like. However, it contains the @support rule which will likelye become more important over time.

This is the desktop table. See also the mobile table.

Last major update on 6 July 2016.


These tests are only about basic support and syntax. Later on I’ll add tests for specific CSS rules, in the hope of finding out how browsers handle edge cases. (For instance, what do you do with font-style: italic when the device doesn’t have an italic font?)

Method or property Internet Explorer Edge 13 Firefox Safari Chrome Opera UC 5.6
8 9 10 11 47 Win 47 Mac 9.1.1 51 Win 51 Mac 38 Win 38 Mac
Basic support No Yes Yes Yes Yes Yes Yes
@supports (display: block) {
	// styles

The styles are applied if the CSS parser recognises display: block as a valid value.

Tested browsers

Desktop browser test array 3.0; July 2016

IE 8, 9, and 10
On separate Windows 7 virtualizations as downloaded from Modern IE.
On Windows 8.1 virtualization as downloaded from Modern IE.
Edge 13
MS Edge 13
On Surface Book with Windows 10.
Firefox 47
Gecko 47
47.0.1 on Win10 and Mac
Safari 9.1.1
9.1.1 on Mac
Chrome 51
Chromium 51
51 on Win10 and Mac
Opera 38
Chromium 51
38 on Win10 and Mac
UC 5.6
Chromium 48
5.6 on Windows 7

Operating systems

Mac Mini with OS 10.11.15
This is my main test station. It also runs all virtual Windows systems.
Windows 7 and 8.1
All downloaded from I use Parallels, and downloded the Windows 7 systems for all browsers but IE11, which runs on Windows 8.1.
Windows 10
Microsoft Surface Book with Windows 10