Not really my desktop (I use KDE with dark theme), but I'll post this as a joke, guess what it is:
Nice to see someone rocking i3 without gaps!
It's definitely a text-based browser, but I have no idea which one haha. Which one is that? I saw some of those on the AUR, and as much as I like cli-based apps, I prefer to use a graphical browser with an extension for VI-like navigation.