[csswg-drafts] [css-overflow] Clarify what rect clips the root element with overflow:hidden on mobile environments with dynamic toolbar (#5646)

hiikezoe has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-overflow] Clarify what rect clips the root element with overflow:hidden on mobile environments with dynamic toolbar ==
The spec says what overflow:hidden means is [the box’s content is clipped to its padding box](https://drafts.csswg.org/css-overflow-3/#valdef-overflow-hidden), and I believe the padding box of the root element is the initial containing block (which is 0-padding) (or maybe the layout viewport?).

On mobile environments with dynamic toolbar, the initial containing block doesn't include the dynamic toolbar height (it's not yet spec-ed though as far as I know of), all major browsers (Chrome, Safari and Firefox) do so.  So, I think overflow:hidden should clip the root element to the ICB (which is not including the toolbar height). But both on Chrome and Safari, the root element clips to the area including the dynamic toolbar, thus regions initially overflowed by the dynamic toolbar can be reachable by swipe up motions.
(note that I intentionally ignore cases where the minimum-scale is applied)

https://bug1663634.bmoattachments.org/attachment.cgi?id=9182769 is an example to show the issue.

CCing @bokand

(Though the behavior both on Chrome and Safari is pretty weird for me, I think Firefox has to align with it. )


Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/5646 using your GitHub account


-- 
Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Thursday, 22 October 2020 01:42:07 UTC