
Pale Moon 27.6Desktop Environment: KDE Plasma v5.11.5, OS: GNU/Linux; Distribution: Arch Linux
To see how it fits in the desktop, here's the link to the gallery for more:
https://postimg.org/gallery/16p5jqa4g/
It has been this way for several months or more, it's so neutral that I may have set this back in 2016 and I wouldn't have noticed, I have organized the window decoration to have it's buttons on the left side of the screen, as well as the window title.
On my desktop (pictures on the aforementioned gallery) I have two panels, organized in a way that the panel with the taskbar goes behind the window when the application is active (or maximized), just waiting for a mouse hover on the first column of pixels where it is at to be visible again and on the top right of the screen, the panel with the status bar, notifications drawer, clock and other useful stuff is, free to be on top of any application's title bar decorations (pretty much all of them to me). That helps to save 20 pixels of real estate on the y axis at any time, and 40 on the x axis when any application is maximized, and it has my personal preference baked in.
The typeface used on Pale Moon User Interface is called Ubuntu (by the Ubuntu distro folks).
The icon set is called Breeze, it doesn't apply to the extensions' icons and some icons that Pale Moon uses.
The theme (persona) is called "I like the gray", by tahomadesign. I matched my desktop's color scheme to this gray, to be as seamless as possible and incurring less eye strain.
Thanks to this post, I'm going to see if I need all those extension icons there yet, since I haven't been using some of them.