I mostly use Open in Reader View(1), but there's also Automatic Reader View(2), which fits your description better. (1) https://addons.mozilla.org/firefox/addo

I mostly use Open in Reader View(1), but there's also Automatic Reader View(2), which fits your description better. (1) https://addons.mozilla.org/firefox/addon/reader-view/ https://addons.mozilla.org/firefox/addon/reader-view/ (2) https://addons.mozilla.org/en-US/firefox/addon/automatic-reader-view/ https://addons.mozilla.org/en-US/firefox/addon/automatic-rea...