## Summary
- paint the community rail across the full app height instead of
exposing the parent background through external margins
- preserve the existing community-button alignment and balanced
horizontal gutters by moving vertical spacing inside the rail
- update the rail geometry coverage to require full-height paint
ownership
## Root cause
PR #2972 aligned the rail box with the inset content by adding top and
bottom margins to the `bg-sidebar` element. Margins are outside the
painted box, so flat light and dark themes exposed a differently colored
app background above and below the rail.
## Validation
- pre-push `desktop-check`
- pre-push desktop unit suite: 3,751 passed
- `git diff --check`
Local Playwright/E2E was not run; CI owns the full browser matrix.
Signed-off-by: Wes <wesbillman@users.noreply.github.com>
Co-authored-by: Carl <c7ebe626f000404285d3686e1dc74cc07cc60a9754a150041ba132e14bd3e2ec@buzz.block.builderlab.xyz>