Allow adding delimiter/seperation bar freely in between tabs?

[MaxHasBeenUsed]

You can manually add them wherever you want, like in right here. As well as allow dragging to move them or deleting them.

It's supposedly to act like a way to organize tabs by separating them (or grouping them, depends on how you see it.) One level lower than "containers".

[ChilledMoth]

Not sure what you're trying to do, but '.Tab[data-lvl="0"]' gives you the root level tabs..

.Tab[data-lvl="0"] {
  border-top: 1px solid #3F3F46;
}

.Tab[data-lvl="0"]:first-child {
  border-top: unset;
}

[MaxHasBeenUsed]

Basically just like this. But I want the option to add this "solid line" wherever I want, not on top of every root level tabs.

[ChilledMoth]

With CSS alone you can still select specific tabs by title, but if you want to be able to place them dynamically or maybe even drag them around it would require code changes. Raise a feature request.

[MaxHasBeenUsed]

I will, once there is anyone else want it. That's why I choose to post in discussion in the first place.

[JohnVKRDam]

I would certainly be interested in this! Just like I love the separators that are available in Bookmarks! It would GREATLY help organizing my thousands of tabs!! :)