2039854 - Container tab line exceeds horizontal tab in Nova with pref enabled

Status: RESOLVED WORKSFORME

(Firefox :: Tabbed Browser, defect, P3)

Description

[Merci chao]

Attachment: Region.png

While bug #2026252 fixed the issue of the container line going out of bounds in Nova, it introduced a “new” design that looks awkward and inconsistent. Wouldn’t it be better to keep the line contained within the tab for a cleaner appearance?

.tabbrowser-tab[usercontextid] > .tab-stack > .tab-background > .tab-context-line {
  position: absolute;
  top: var(--tab-block-margin);
  margin: 0;
  width: calc( 100% - var(--tab-min-height) + 6px );
  align-self: center;
}

Comment 1

[BugBot [:suhaib / :marco]]

:nsharpley, since you are the author of the regressor, bug 2026252, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 2

[Stephen Thompson [:sthompson]]

Yes, I think that would look nicer. We have bug 2035553 coming up to optionally make the UI more compact -- I think we can do another pass on this when we have a better idea of what the width calculation would need to be. I'm not sure that a hardcoded 6px will look consistent on all platforms and UI density.

Comment 3

[Merci chao]

Attachment: Region.png

(In reply to Stephen Thompson [:sthompson] from comment #2)

I'm not sure that a hardcoded 6px will look consistent on all platforms and UI density.

Theoretically, width: calc(100% - var(--tab-min-height)) is the correct answer. However, in practice, the line does not visually cover the whole straight part of the outline. Using 6px in the sample above is somewhat arbitrary, and perhaps 4px or less would be a better choice.

Comment 4

[BugBot [:suhaib / :marco]]

This bug has been marked as a regression. Setting status flag for Nightly to affected.

Comment 5

[Stephen Thompson [:sthompson]]

Note: we may support adjustable tab border-radius around the 155 or 156 releases. If we do that, then a CSS rule based only on tab height would not be sufficient. Let's try to solve for every combo of normal/compact/touch density + round/smooth/sharp border-radius variations.

There is also some discussion about changing the container tab styling to a full colored border around the tab, but at this moment I'm not sure which release that might be targeting.

Comment 6

[Merci chao]

Attachment: Region.png

Need to take a look on split views. 153.0a1 (2026-06-12)

Comment 7

[Stuart Colville [:muffinresearch]]

Hi Baku, wondering if this might be a dupe of some of your styling changes?

Comment 8

[Andrea Marchesini [:baku]]

correct. this is should be fixed in the latest nightly + there is a patch in review.

Comment 9

[Merci chao]

Attachment: Region.png

I'm confused with the change in 155. The container line has become hard to recognize and is still cut off in split view, but this time it's covered by the site icon in compact mode.

In fact, simply adding overflow: visible on the tabs in split views will make the line fully visible, although I'm not sure what side effects it might have.