1650293 - Background-color in dir:first-of-type is not working on Firefox 78 and 79

Status: RESOLVED INVALID

(Core :: CSS Parsing and Computation, defect)

Description

[prada960808]

Attachment: poc_min.html

User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36

Steps to reproduce:

1. download Firefox binary from https://ftp.mozilla.org/pub/firefox/releases/ (76.0b8, 77.0b9, 78.0b7, 78.0esr, 79.0b2)
2. open poc.html on Firefox 76.0b8, 77.0b9, 78.0b7, 78.0esr, 79.0b2

Actual results:

Background-color in dir:first-of-type is not working on Firefox 78 and 79.
The rendering results of Firefox 76.0b8, 77.0b9 and 78.0b7, 78.0esr, 79.0b2 are different.

Expected results:

Background-color in dir:first-of-type should be black.

Comment 1

[prada960808]

Attachment: 77.0b9.png

Comment 2

[prada960808]

Attachment: 78.0esr.png

Comment 3

[Alin Ilea, Desktop QA]

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0

Hi,

I have managed to reproduce this issue on Release version 78.0.1, Beta 79.0b5 and latest Nightly 80.0a1 (2020-07-08) using Windows 10.

Further, I will move this over to a component so developers can take a look over it. If this is not the correct component please feel free to change it to an appropriate one.

This is a regression, here is the pushlog:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=3f463aabe0de79354acec0c38f348633bbcdeff0&tochange=9bedd57840edbba0a91f41e8347a6a724473d13a

Thanks for your report.

Comment 4

[Emilio Cobos Álvarez (:emilio)]

This is invalid. After bug 312971 input:read-only matches and thus the input takes space and shifts the <dir>. Our rendering of the test-case matches other browsers, afaict. The background rule still applies and works just fine.

Comment 5

[prada960808]

(In reply to Emilio Cobos Álvarez (:emilio) (PTO until Jul 10) from comment #4)

This is invalid. After bug 312971 input:read-only matches and thus the input takes space and shifts the <dir>. Our rendering of the test-case matches other browsers, afaict. The background rule still applies and works just fine.

Unlike Firefox 77, it is not possible to see the background color (black) in Firefox 78, 79, 80.
Which one is correct?

Comment 6

[Emilio Cobos Álvarez (:emilio)]

Firefox 78+ is correct. Previous versions of firefox didn't recognize input:read-only { min-height: 89vh;. If you remove that rule from the test-case FF78+ behaves the same as previous versions of Firefox.