Duolingo top tip!
uBlock Origin is an adblocker for Firefox. If you have it installed and then right click the ad elements in Duolingo (They add a company ad saying "we see you use a free adblocker, why not pay us and we'll do its job for you...(???) and try to push their premium subscription on you in other places too) you can select the elements of the page you want to get rid of with a feature of uBlock Origin! The elements simply don't exist on my Duolingo page any more because the adblock filters them out.
THIS WORKS FOR POPUPS on other pages too!!! If the page is loaded and then hidden behind a popup that stops you reading the page, getting rid of the elements by right clicking them and adding them as an element uBlock Origin removes can restore functionality to the page! :)
@pfx oh, that's what I used as an adblock for years: deleting parts of the page in developer console (right click, inspect element, smash delete)
@pfx You can also bind the element zapper to a keyboard shortcut to quickly dig out the content from under the layers of pop-ups
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