autohide_tabstoolbar_v2.css broken in FF135

[Stoarr]

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I'm using autohide_tabstoolbar_v2.css with vertical tabs and the sidebar seems to be broken. FF doesn't let me collapse the sidebar and wants to push (but fails) the window behind the sidebar area when I click the sidebar button. With sidebar on the right it only expands the tab bar out of the sidebar area instead of the whole area