Remove empty space at the top when side tabs are enabled

[genius8loci]

Please make it so that when the side tabs are enabled, it does not leave empty space at the top, but fills the address bar with other elements.

A huge omission is that for this customization you need to put one of the custom themes from the site
https://firefoxcss-store.github.io/

I've tried 3-4 variants, they somehow break when working with other plugins and themes that are native to the browser.

What I'm asking for is implemented in the themes:
https://github.com/Naezr/ShyFox
https://github.com/zayihu/Minimal-Arc

And ShyFox is perfect for me, what I would like the browser to be without "additional customizations".

[Jon]

Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.

[genius8loci]

Made a little sketch in a screenshot of what I had in mind when I wrote this idea from my phone.

[sfoster]

We're still actively working on this feature, and collapsing the horizontal tabstrip toolbar when you enable vertical tabs is coming - its just not complete yet.

[SniperFox]

Came here looking for this.  Is there an addon that will do it temporarily until the official final solution is ready?

[Jon]

This has been delivered. With the latest Nightly with Labs experiment on, there's no lingering empty space at the top.