I want to use this too.
Updated the FAQ to include the font information:
I don’t think that’s Fira Mono. If you pay attention to the @ and the
0 (zero), they are quite different. I believe that’s the default monospace font for the Mac, Menlo. There is this open source version of it here, called Meslo.
You’re right. I was looking at the screenshot in the one-dark-vivid-syntax theme README. Updated the FAQ again.