🐞Livestream comments sidebar cinema mode bug

Concise Description

When comments are set to sidebar mode and a livestream with chat window is open, setting browser window to half-screen and then enabling cinema mode will cause empty sidebar to appear instead of video taking up full horizontal view.

Browser/s

Firefox

Other Browser:

No response

'Steps to reproduce' - Which of our features is required for the bug to happen?

Enable comments sidebar. Open a livestream. Enable chat view. Snap browser window to side. Enable cinema mode.

Since when?

At least 14/6/26

Does the bug still happen when you log out of YouTube?

None

..No? Then please paste your yt.config_.EXPERIMENT_FLAGS. Twice (With the error & Without)

No response

Are any errors or related log-messages shown in the Browser-Console? (F12)

No response

Tested as the only active extension? (incognito mode or another browser users):

None

Expected preferred behavior:

No response

ImprovedTube Version

No response

Your Settings (From the Extension's ⋮-Hamburger menu > Settings > Backup & reset > Export settings)

No response

Your YouTube-Document

No response

OS / Device:

No response

Reproduce the issue in Firefox using the reported sequence: enable the comments sidebar and chat view, snap the browser to half-screen, then enable cinema mode. Trace the frontend layout handling for the sidebar and cinema mode; done means the video fills the horizontal view without an empty sidebar.