I think this is more robustly solved by just collapsing headings and letting the user expand them if they want. See: Wikipedia on mobile. The issue with the aut

I think this is more robustly solved by just collapsing headings and letting the user expand them if they want. See: Wikipedia on mobile. The issue with the author's approach is that you don't know what information you are gaining/losing by switching between modes, and the onus is on the author to decide what information is available at each tier. What's unnecessary trivia for one reader may not be for another.