Aw shucks! It is indeed d3, and, as per the commenter below, uses very very lightly adapted tufte.css for layout.

Agreed. Those are awesome visualizations.

According to the Chrome console output they all appear to be D3 visualizations.

The way the layout uses the right margin for legends or auxillary information, or how the charts sometimes bleed into that space looks straight out of a Tufte book. :thumbsup: