Description of the new feature/enhancement

It would be great if the backgroud color also applied to the title bar, for example, this is the terminal with a custom background color:

This is how it should look with the added feature (supposing the thick white border issue was fixed as well):

I think the tabs color doesn't look the best either, I don't have any ideas but maybe adding some opacity to them would look better...

Proposed technical implementation details (optional)