How can I hide the TST header?

[mfn]

Apologies if this has been asked, couldn't find it in issues/discussion nor something in the prefs; I would like to remove this part outlined in red:

In fact, I have not see this in a long time but when I restarted FF into 91.0 yesterday, it appeared. The X closes the whole TST, not just the header 😅

Thank you!

[irvinm]

The sidebar header can be modified via userChrome.css. What code were you using previously to hide it? Are your other userChrome.css changes still working?

[mfn]

The sidebar header can be modified via userChrome.css

Hmm, I don't have any and I don't recall it having TST modified through this.

I also don't have other add-ons modifying user styles.

All I know is that from one restart to next, this big header suddently appeared where none was before (for … months? … at least a long time)

[irvinm]

Well, that is interesting. Regardless, I think userChrome.css you are looking for is here: https://github.com/piroor/treestyletab/wiki/Code-snippets-for-custom-style-rules#hide-the-tree-style-tab-header-at-the-top-of-the-sidebar

[mfn]

Thank you, this worked like a charm!