Light theme code coloring

[rossabaker]

Spinning off from #573, discussing a light code theme to go with the light overall theme.

light theme code highlighting is a bit trickier imo

CW: Emacs

Protesilaos Stavrou put a lot of effort into his Modus color palettes for Emacs. WCAG conformance is an explicit design criterion, and Modus Operandi (sample) is my daily driver. I don't know whether it would clash with Typelevel Red, but it's a great starting point.

[j-mie6]

Definitely something I want to look into 🙂 may be a bit of time before I can afford to get around to it (@armanbilge feel free to assign me!)