This was for <code> tags, which we don't have here. The rest is
already all monospace and Source Code Pro has bugs on macOS.

Unfortunately the normal font families like "sans-serif" and
"monospace" are basically broken because the browser defaults are
decades old.
TODO: Inline code is barely distinguishable.

This allows it to be distinguished not just based on the font.
Not adding a border because that's a bit much.