Posts
Comments
Good question. I will try to explain why the typography is noteworthy, rather than the mechanics of making it so. First, the small sans-serif font here is exceptionally readable. That isn't easy. Site-specific browser magnification is typically necessary on other websites.
Next, there is the range of choice offered within the user interface for comments. Having a choice of LaTeX, markdown, rich text (as well as built in features such as footnotes) for posts would be unusual, yet LW offers it for comments as well!
Finally, please see gwern's examples for LW2 linked above. I find GreaterWrong challenging to read, and confusing to navigate. Not for me, but maybe for thee! ReadTheSequences uses serif fonts but has traditional typographical elements that give it elegance, yet is still spaced and kerned such that it is easily readable. The more elegant typeface is used sparingly, for important LW1 posts which is part of good typography too. Hope that helps.