Gnome 4 Active Window Titlebar

I am a new convert to Fedora Linux, Gnome desktop, and one thing that keeps tripping me up is that active window titles look pretty much identical to inactive ones. This often causes me to close the wrong window as I have a large monitor with 6 or 7 windows tiled at any given time. What I want to do is customize the active window title so that I have a strong visual cue as to which windows is active at any given time. I have created a ~/.config/gtk-4.0/gtk.css file, with the following:

`
headerbar,
.titlebar {
    background                          : #9D4904 linear-gradient(to bottom, shade(#9D4904,1.2), shade(#9D4904, 0.8));
    border                              : none;
    border-radius                       : 0;
    padding                             : 2px;
    transition                          : 200ms ease-out;
    }

` which works for almost everything (a notable exception being browser windows). However on some windows there's an inexplicable gap at the top: And on on some others part of the titlebar has a gap at the bottom and top: Any help in eliminating this (and for browser windows, too!) would be much appreciated. I've tried all manner of guesswork at what the CSS tag/class for the container might be, and all manner of padding settings, which have all had no effect.