1431933 - Firefox 58 - some @media rules get ignored in userChrome.css (and maybe in extensions) [fine with Firefox 57/59]

Status: RESOLVED DUPLICATE of bug 1418963

(Firefox :: Theme, defect)

Description

[Aris]

User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0
Build ID: 20180118215408

Steps to reproduce:

Create a userChrome.css inside profiles 'chrome' folder.

Add an example like this

@media (-moz-os-version: windows-win7) {
	toolbar {
	  background: red !important;
	}
}

@media (-moz-os-version: windows-win10) {
	toolbar {
	  background: blue !important;
	}
}


Actual results:

Executing this code on Windows 7 should colorize all toolbars red and on Windows 10 blue. Instead nothing happens, because "@media (-moz-os-version: windows-win7)" and  "@media (-moz-os-version: windows-win10)" get ignored and throw warnings in console.

"Expected media feature name but found ‘-moz-os-version’."


Expected results:

Code should get applied as specified.

This issue only occurs on Firefox 58 (release, beta, Nightly). Firefox 57 and Firefox 59 are not affected.