1810174 - Collapsed section unfolds its content upwards instead of downwards

Status: NEW

(Core :: DOM: Core & HTML, defect)

Description

[Christian Sadilek [:csadilek]]

From github: https://github.com/mozilla-mobile/fenix/issues/17405.

Steps to reproduce

In some websites when I click in a collapsed element to unfold its content, the content reveal is done upwards instead of downwards, showing you the end of the element instead of the start of the revealing.

I'll try to explain with an example of the bug which is affecting a spanish aggregator website named Meneame.

If you go to some article in www.meneame.net you'll find that the full comment section is semi-hidden inside a collapsed element when there are many comments, with a button to unfold it. The problem is that when you click the button the rest of the hidden comments don't appear down. Instead they appear up, so you lose the focus of the comments timeline.

Example: https://www.meneame.net/story/siete-autobuses-emt-abandonados-temporal-amanecen-bandalizados
I'll attach some video to show the wrong behaviour and how it should be (as it is in Chrome).

Expected behavior

In this Meneame example, when the comment section is unfold it should be done downwards in order to not lost the comments timeline reading.

https://user-images.githubusercontent.com/17139675/104248438-c8acd000-5469-11eb-894b-b4a70fe1ca87.mp4

Actual behavior

The hidden section is unfold upwards, so your view remains in the endpage and you lose the focus of the comments timeline.

https://user-images.githubusercontent.com/17139675/104248452-cea2b100-5469-11eb-9807-629276b8ad89.mp4

Device information

• Android device: OnePlus 8 with Android 11
• Fenix version: Firefox for Android 84.1.4 (Build #2015785883). It's also happening in Firefox Nightly 210110.

┆Issue is synchronized with this Jira Task

Change performed by the Move to Bugzilla add-on.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:cpeterson, could you have a look please?

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Comment 2

[Kayacan Kaya [:kaya]]

Forwarding this ticket to another component in case it belongs there. Otherwise, please feel free to forward it back or to the responsible component.