But I think they have used a special format.

As you can see from the new picture I have linked, the side numbers are still in front (not disappearing behind like what happened to me when I tried to make a textbox), and the heading also has the same grey color from the tab on the right side.

Link to new picture: Skjermbilde-2021-03-12-kl-23-03-02 — ImgBB