I think the default target is expecting a smaller screen mobile device, hence the 13px default. This is a good idea, and any other screen sizes that see smaller text can still zoom in using default browser behaviors.

I disagree. When I saw the page, I thought, "Finally an information dense page again! It's been so long since they've been common and I miss them."

Agree, even just converting to use em instead of px is more usable on differing screen size/dpi

Yup. Even on mobile the text is too small for me. In particular, the line-height could be larger so links can be tapped more easily.

Nice though, I like it.

This has been patched. Thank you.