Print-derived page furniture for genuinely long-form pages — a scroll-linked running folio (current-section head), a marginal read-o-meter (reading time + percent as small-caps type, never a progress bar), a sticky scrollspy section rail, Tufte-style footnote/sidenote gutters in a reserved margin column, and marginal pull-quotes — all set in layout-grid's outer column and degrading to inline superscript + native popover below the gutter breakpoint.
