[Bug]: Page resizing when vertical tab expands

[LiamillionSS]

Pre-Submission Checklist

• I have checked the existing/closed issues to ensure this issue has not already been reported.
• I am using the latest supported version of the browser.
• I have tried disabling all browser extensions/add-ons to rule out interference from these.
• I have tried clearing the browser cache and cookies.
• I have checked with a new profile and the issue still occurs.
• I have provided detailed step-by-step instructions on how to reproduce the issue.
• I have included relevant screenshots or console outputs.
• I have checked that this problem is not occurring in the latest version of Firefox ESR.
• This issue is specific to this browser and does not occur in other browsers.

Bug Summary

The webpage resizes when vertical tab expands. In configurations where the browser is not taking up the full screen (like one half of the monitor is Floorp and the other Discord), this can cause the layout of pages to completely change which is a big distraction.

Reproduction Steps

1. Enable "Vertical Tab Bar"
2. Enable "Collapse Vertical Tab Bar"
3. Move mouse over tab bar to trigger the bar to expand
4. Page resizes and returns to normal once the bar collapses again

Expected Behavior

Webpage should not resize when the vertical tab bar expands

Actual Behavior

Webpage resizes

Screenshots

2025-03-05.02-05-12.webm

Browser Version

11.23.1

Operating System

Arch Linux 6.13.5-arch1-1

Additional Context

No response

[ACR-Jeff]

I can confirm this on void linux as well.

[sameyepatch]

I am using EndeavorOS with 6.13.5-arch1-1, Floorp-bin installed from the extras repository. I can confirm the same behavior. Where it doesn't seem to happen, however, is in the settings page (about:preferences)

[ACR-Jeff]

Well I solved this issue on my end,
Below are the steps I took to solve it.

1. Open Browser Toolbox
2. Go to Style Editor tab
3. Search for Tab
4. Click on native-verticaltab-hover.css
5. Go to line 17 --hovered-verticaltab-width: 20em;
6. Change line 17 to --hovered-verticaltab-width: 35px;

Hope this will help others and can be fixed soon.
This is only a temporary fix until they solve it within the code. For now it just works for the instance until a restart of the browser. I am going to continue looking for a more permanent solution.

[ACR-Jeff]

Well I noticed the above isn't a solution when having a collapsible vertical bar, I had mine set to a specific size in my css. The above is only a solution if you have set a specific tab size in your css. The page is still resizing on expand without modifying a size in your css. I will continue to troubleshoot this.