As good as this extension might be, it appears to not respect the font setting outside of headings. Additionally it seems to have performance issues on larger article.
Example sites: settheory.net, plato.stanford.edu

Only been using this for a few hours, but finding it useful for saving recipes to Evernote. Recipe sites tend to be cluttered with shopping lists or recommended recipes, reviews, and such. But Evernote's built-in "simplified article" clipping mode often removes the featured photo of a recipe along with everything else, which I don't want (Firefox's built-in readability mode often does too). Tranquility (+ uBlock Origin's block element feature) gets rid of most of the junk on sites like Food Network but gives you the option to always keep pictures, so I use Tranquility and then clip to Evernote, which works nicely.

It's also nice that on the many recipes where Food Network annoyingly has only a video rather than a photo, Tranquility hides the video and automatically uses the preview image from the video instead which is exactly what I want and was having to do manually before!

Icon looks weird but app works fine

This is a great customisable reader app which - unlike the firefox native version - allows you to keep images in and hyperlinks highlighted.

The options are a bit clunky - and the default view in my opinion should be with a sans serif font (not Georgia) because this is usually better for readability and accessibility

Thanks to the dev