[kalvinnchau]

Problem

Inline custom emoji (:shortcode: images) look oversized and sunk in message text. .customEmoji renders a 22px <img> with vertical-align: middle inside 14px text. That makes the image about 1.6em tall with its center at half the x-height, so it hangs about 7px below the baseline.

Change

.customEmoji is now 1.125em square with vertical-align: -0.125em, so the image is smaller and drops only 0.125em below the baseline.

Jumbo (emoji-only) messages still set --inline-emoji-size and top alignment, so they are unchanged.

Before / after

Same message row from tests/fixtures/emoji.html with Inter, main vs this branch.

Evidence

• design:check and biome check: pass.
• Playwright emoji, custom-emoji-authoring and reactions specs: pass in Chromium and WebKit (22 tests).
• Not yet done: a human check in the app.

[salman1993]

🤖 Reviewed commit 66cc6677fcfc2a4927eac3b0d5a19d5cd9ba5783. No code blockers found. Minimalness, elegance, and correctness meet the 9/10 bar for this scoped change.

The rule stays with the existing CustomEmoji renderer. Relative sizing follows the surrounding type; the design guide's Foundations section explicitly leaves emoji artwork geometry renderer-owned. Jumbo messages retain their size override and more-specific top alignment. Reactions and composer tokens retain their own geometry rules. Settings and completion also consume CustomEmoji; I found no concrete regression in those uses.

Validation: inspected the callers and CSS cascade, checked the full diff, and exercised the PR-head emoji fixture in the in-app browser with the existing tests' SVG media stand-in. Checked light/dark, narrow/wide, and 150% text sizing, including inline, jumbo, table, quote, and failed-image fallback rendering. Computed inline size is 17.5px at 14px text with baseline alignment; jumbo remains 42px with top alignment. Keyboard completion followed by pointer Send produced a rendered inline custom emoji. I did not rerun the test suites or perform native desktop acceptance.

Readiness remains incomplete:

• Browser measurements and CI required are failing. The WebKit 300-author thread test reports “thread did not finish traversal.” Its stress messages have no custom emoji, so this appears unrelated to the changed rule; this review does not establish the failure's cause or that it is flaky. Failed job.
• The PR description says the human app check is still pending, while the PR is currently ready for review. Per AGENTS.md, keep it draft until human acceptance is confirmed; add buzz-review-completed only after the required review and acceptance steps hold.