The post “Interstellar travel will probably doom the long-term future”, due to its high density of footnotes, works as a sort of stress-test of Less Wrong’s sidenote system. The result is decidedly not great:

(The sidenotes, they do nothing!)

Normally, a sidenote should be approximately adjacent to the in-text citation which refers to that note; in this case, sidenote #32 is pushed down, way out of the viewport, by the other sidenotes. (Hovering over a citation highlights the associated sidenote… which is, of course, useless when the sidenote is beyond the viewport’s bounds.)

My own solution (implemented for gwern.net) is what I call “slidenotes”. (They’re sidenotes that slide into view.)

For example:

(Sidenote #12 is below the viewport.)

Then, the user mouse-hovers on citation #12:

(Sidenote #12 has moved into view.)

Code for this feature (as for all gwern.net features) is, of course, available on GitHub.