That's WSL+ZSH running in ConEmu (w/ Solarized Dark color theme).

I also have this theme installed on Windows 10, which is why everything is dark including the ConEmu's titlebar: http://www.cleodesktop.com/2016/08/after-dark-cc-theme-for-w...

I spend long hours staring at the screen, I need a dark theme for eyesight preserving reasons. I had a dark theme on OSX until Apple decided to give a massive middle finger to the theming scene when they released El Capitain. The built-in dark mode just doesn't cut it. Yet another reason I'm glad im on Windows now.