Minor gripe - These sort of tools always deride matplotlib a bit, but often show outright incorrect examples of using it.

Admittedly, the "right" way of doing it is quite clunky as well:

    ax.xaxis.set(major_formatter=StrMethodFormatter('{:0.0f}%'))

The example shown teaches very bad habits. It doesn't change the tick label formatting at all. It makes the ticks and labels static. There's a big difference, and it's obvious as soon as you interact with the plot (i.e. zoom/pan around - you won't get new ticks/labels).

I agree that matplotlib isn't the right choice for web-based visualization, but let's not pretend it makes static plots. It's a very, very highly interactive desktop visualization package, and oriented towards building desktop applications that can produce publication-quality plots.

All that having been said, this looks pretty neat.