Sidenotes: Marginalia for the Web

Typography on the web has always lagged behind print. One of the most useful tools available to print designers — the marginal note — has been largely absent from web writing. This post demonstrates a pure-CSS sidenote implementation no JavaScript required The entire toggle mechanism on mobile works via the HTML checkbox hack: a hidden <input type="checkbox"> paired with a <label>, toggled by the CSS :checked pseudo-selector. No JavaScript is loaded or executed. that works at any viewport size. ...

March 13, 2026 · 3 min · Marcin Cylke