[css-position] What is the behavior of an absolutely-positioned <br>?

[smfr]

https://drafts.csswg.org/css-position/#position-property is clear that position applies to the <br> element, and that "the box is taken out of flow such that it has no impact on the size or position of its siblings and ancestors, and does not participate in its parent’s formatting context." It also say "A position value of absolute or fixed blockifies the box and causes float to compute to none."

This implies that the <br> should not trigger a line break here:

text
<br style="position: absolute;">
here

However, WebKit and Blink both trigger a line break. Gecko does not.

[smfr]

Similar story with float:

text
<br style="float: left;">
here

[fantasai]

I agree with Gecko here fwiw. Having it continue to trigger a line break would make <BR> behave rather differently from any other out-of-flow.

[fantasai]

Agenda+ to suggest closing no change.

[css-meeting-bot]

The CSS Working Group just discussed CSS Positioned Layout, and agreed to the following:

• RESOLVED: Close no change: taking BR out of flow removes its effect on the surrounding content, just like every other element

The full IRC log of that discussion

<fantasai> Topic: CSS Positioned Layout
<fantasai> github: https://github.com//issues/5749
<fantasai> Rossen_: Seems the proposal is to close no change.
<fantasai> smfr: Question is if you have a <br> and say 'position: absolute'. Does it trigger line breaks?
<fantasai> smfr: 'position: absolute' takes it out of flow
<fantasai> smfr: which probably means it shouldn't trigger a line break
<fantasai> smfr: so I think Gecko has the right behavior
<fantasai> smfr: Slight concern about if it's web-compatible, but if Gecko's shipping probably OK
<fantasai> Rossen_: do we have any specific spec text defining it one way or another?
<fantasai> smfr: I think the spec is fine, just implementers not following spec
<fantasai> florian: That and fact that BR and WBR aren't properly specced fully
<fantasai> florian: we've had discussions about how to represent them, but haven't fully resolved
<fantasai> florian: but only logical behavior is if take out of flow, stop influencing the text round it
<emilio> q+
<fantasai> Rossen_: sounds like we have consensus for breaking behavior here
<fantasai> Rossen_: and that seems to be spec-compliant atm
<Rossen_> ack emilio
<fantasai> emilio: I've never heard a compat issue with Gecko's behavior so far
<fantasai> Rossen_: proposed close issue no change to spec and encourage UAs to follow Gecko's lead
<fantasai> RESOLVED: Close no change: taking BR out of flow removes its effect on the surrounding content, just like every other element
<astearns> A testcase would be an excellent encouragement (and smfr just added the tag to the issue)
<fantasai> emilio: Where does the WebKit behavior come from?
<fantasai> smfr: It's probably very historical
<fantasai> iank_: BR inherits from text node, so has ...

[smfr]

WebKit bug: webkit.org/b/230048