Refine the monochrome theme

[badlydrawnrob]

For now: bold is 400, removed HTML underlined tags, grey comments in Print-First-CSS. You'll also need to check colours for accessibility.

I've collected a variety of monochrome themes offline and would be nice to make some minor adjustments to Print-First-CSS default. I'm not happy with the bold (especially with Racket Lang) and I'd prefer it to be more subtle. I use it sparingly for notes fields, and considering using it on occasion on the front of Draw! card.[^1]

[^1]: I'm purposely making it a non-dark theme (when used in the Draw! card) for two reasons: (a) It might be better to enforce an image-only front for the Draw! card, and (b) the image should definitely be front and centre. A dark theme here is way too distracting. The reverse of the card can use the dark theme.