## Summary

`body { zoom: 1.25; }` (`src/scss/_layout.scss`, confirmed live since at
least 2026-04-11, likely earlier — `muse blame` couldn't reliably date it
due to a separate false-attribution bug filed as muse#84 in the muse repo)
is the root cause of a class of layout bugs where `position: sticky` and
`100dvh`-based height calculations misbehave. `zoom` is a non-standard CSS
property (WebKit/Chromium-originated) that rescales the entire layout box
model including viewport-unit math and sticky offset calculations, in ways
that are inconsistent across engines.

musehub#84 / the two-column-scroll-layout fix worked around this by avoiding
`position: sticky` entirely (bounded-height flex/grid with independent
`overflow-y: auto` per column instead) — but `zoom` itself is still present
and will keep causing friction for any future layout work that assumes
standard viewport-relative math.

## Why not fixed now

Removing `zoom` outright and replacing it with `rem`-based font scaling (the
standard equivalent) is blocked: the design system's spacing tokens
(`--space-*`) are currently defined in `px`, not `rem`. Without `zoom`,
`px`-based spacing wouldn't scale with the intended 1.25x zoom effect, so
removing `zoom` requires first converting spacing tokens to `rem` — a broader
design-token refactor, not a drop-in swap.

## Proposed investigation

1. Audit `--space-*` and any other `px`-based design tokens for feasibility
   of a `rem` conversion.
2. Prototype removing `body { zoom: 1.25 }` in favor of `html { font-size: 125% }`
   (or equivalent) once tokens are `rem`-based.
3. Re-test all pages that use `position: sticky` (if any remain) and any
   `dvh`/`vh` viewport-unit calculations for correctness once `zoom` is gone.
4. Decide whether the bounded-height/independent-scroll pattern introduced in
   musehub#84 should be kept regardless (it's the more idiomatic, cross-browser
   pattern for independently-scrolling columns even without `zoom` in the
   picture).

## Impact

Not urgent — the concrete symptom (broken two-column scroll) is already
fixed. This is forward-looking: `zoom` remains a landmine for any future
CSS relying on standard viewport-unit or sticky-positioning math.