As an example of differentiating different kinds of footnotes, waitbutwhy.com uses different appearances for “interesting extra info” notes vs “citation” notes.
Both kinds also appear as popups when interacted with (certainly an advantage of the digital format).
(Specifically, asides are given superscript large blue circles with numbers inside; while mere citations/sources are given instead a small faded gray box with numbers. They are separately numbered. The footnote popups themselves are fairly standard click-to-popover.)
As an example of differentiating different kinds of footnotes, waitbutwhy.com uses different appearances for “interesting extra info” notes vs “citation” notes.
Both kinds also appear as popups when interacted with (certainly an advantage of the digital format).
(Specifically, asides are given superscript large blue circles with numbers inside; while mere citations/sources are given instead a small faded gray box with numbers. They are separately numbered. The footnote popups themselves are fairly standard click-to-popover.)