Gnome 3.28 - Better Focus Window Visibility

gtk.css

/* File ~/.config/gtk-3.0/gtk.css */

.titlebar {
    color:white; 
}

.titlebar:backdrop  {
    background: #333;
    color:#666;
}

@define-color decoration_border_color #666;
@define-color decoration_border_color_unfocused #333;

/* focused window */
decoration {
    border: 1px solid @decoration_border_color;
    background: @decoration_border_color;

    /* switch colors smoothly with a transition animation */
    transition: border-color ease-in 0.2s, background-color ease-in 0.2s;
}

/* unfocused window */
decoration:backdrop {
    border-color: @decoration_border_color_unfocused;
    background-color: @decoration_border_color_unfocused;
}

/* focused window (server-side rendering hack) */
.ssd .titlebar {
    border: 1px solid @decoration_border_color;
    border-bottom: none;

    /* transition animation does not seem to work with server-side rendering */
    /* transition: border-color ease-in 0.2s; */
}

/* unfocused window (server-side rendering hack) */
.ssd .titlebar:backdrop {
    border-color: @decoration_border_color_unfocused;
}

/* remove borders of maximized windows */
.maximized decoration,
.ssd.maximized .titlebar {
    border: none
}