Type for Interfaces
A brief argument for the serif in your sidebar.
Duis aute irure dolor in reprehenderit. Most interface type is sans-serif for reasons that made sense in 2010 and haven’t been re-examined since.
The case for a serif
A well-drawn serif at 16–19px is not harder to read. It’s harder to skim, which is sometimes exactly the point — in an article, in a case study, in the body of a long email.
The case against overcorrecting
I’m not arguing for a serif everywhere. The list, the toolbar, the form label — those are navigational. Use the sans. Use the mono.