Though they are linked, see e.g. <a href="http:&#x2F;&#x2F;rhythmus.be&#x2F;md2indd&#x2F;#fn2" rel="nofollow">http:&#x2F;&#x2F;rhythmus.be&#x2F;md2indd&#x2F;#fn2</a> — it’s Pandoc after all, which creates those ;-)<p>The wide margins are due to typography best practices, which dictates between ~50 and 70 characters on a line. One could of course blow up font-size, as is in fashion, since Medium. But then there are too few lines above the fold.<p>But you’re entirely correct as regards marginal notes. Unfortunately, they’re not trivially implemented, since you’d need to swap end-notes to side-notes relative to the viewport, cq. media query breakpoint, but while that involves DOM manipulation, it cannot be done with CSS alone. Let alone dealing with collision detection for stacking longer footnotes vertically…