Kill Sticky Headers

On Firefox I use extension Hide Fixed Elements for this [0] because it gives me a toolbar button (although I'm wishing for a keyboard shortcut) that makes it easy to turn it on and off.

However, adding that bookmarklet to the browsers on my phone has been the biggest life saver - it's crazy how often I hit a site where only ~30% of my screen is dedicated to content and the rest are sticky headers or footers.

[0]: https://alisdair.mcdiarmid.org/kill-sticky-headers/