#compose-sidebar only had its flex-column + gap:16px declaration
inside the desktop media query, so on mobile the inbox/shared/sent
cards stacked as plain blocks with no deliberate spacing. Move the
rule to base CSS so the rhythm between inbox → shared → sent
matches the compose → inbox gap regardless of viewport width.
Desktop re-declares it next to the grid layout for clarity; the
duplication is harmless.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>