Each AvatarTile rendered at `size × size` with a 2px border under
`box-sizing: border-box`, giving a content area of `(size − 4) × (size − 4)`.
The inner `<Avatar size={size}>` exceeded the padding box, and the
`overflow-hidden + rounded-full` clip — centered on the wrapper — combined
with the avatar contents anchored at the padding-edge top-left to displace
photos and especially the centered initials gradient + letter toward the
lower-right of the visible disc, leaving a sliver of background opposite.
Compounding this, `Avatar`'s `inline-flex` root sat on the line-box text
baseline, so any inherited `line-height ≠ 1` (the DM list inherits the
row's line-height) drifted the avatar a further several px vertically.
Two corrections:
• Size the inner Avatar to `size − 2·TILE_BORDER_WIDTH` (matches the
padding box) — extracted as a constant so the dependency between
`border-2` and the inner size is visible.
• Center geometrically via `flex items-center justify-center` on the
wrapper, bypassing inline-flow placement so the Avatar is anchored
regardless of inherited type metrics.
Verified in the live app (DM sidebar, chat header, welcome header) and
with a 4-tile diamond at sizes 32 and 80: visible offset is now exactly
the border width on every tile, letters/photos sit dead-center.
Adds a regression test that pins both invariants (flex centering classes
present + inner Avatar style.width === tileSize − 4) so a future change
that re-introduces the bug fails fast. 12/12 AvatarStack tests, 365/365
web tests, typecheck clean.
design-system.md spec updated with the AvatarTile geometry contract.
Jannis Braun
87ecf0f4f3