brent you had me at about:config
Well, it's ok as long as they allow us to. They tend to clean up tasks like this after a while.
Design changes are often an acquired taste. But I think this search bar change is ridiculous!
I personally have another matter, which I whish I could change. I am using the dark theme and always have lots of tabs opened. In the tabs list you see the dark theme working. Links are white and the current tab link is bold, Scrolling through changes background slightly to darkgray. This IMHO does need a current tab focus background highlight color, which you can spot immediately. I know it must be a matter of a personal userChrome.css file. But I dont know what selectors to tweak, since you / I can't use developer tools on this.