Some websites have "sticky" headers. Depending on your preference settings and browser, some of those headers cover a third of the screen or more and do not go away as you squint and scroll through the tiny window that remains.
Now you can kill sticky headers, open your eyes and see the whole screen for you scrolling pleasure. One click on this bookmarklet turns off stubborn, view-blocking headers. To restore headers, simply refresh the web page. I love it.
Check this out. https://alisdair.mcdiarmid.org/kill-sticky-headers/