diff --git a/.github/workflows/release-qa-browsers.yml b/.github/workflows/release-qa-browsers.yml
new file mode 100644
index 0000000..4b35dd9
--- /dev/null
+++ b/.github/workflows/release-qa-browsers.yml
@@ -0,0 +1,45 @@
+name: Throughline release QA browsers
+
+# Additional, read-only release-candidate verification. The regular CI
+# retains Chromium and the distributable/consumer checks.
+on:
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: throughline-release-browser-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  cross-browser:
+    name: Browser regressions (${{ matrix.browser }})
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    strategy:
+      fail-fast: false
+      matrix:
+        browser: [firefox, webkit]
+    steps:
+      - name: Checkout source
+        uses: actions/checkout@v6
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v6
+      - name: Setup Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          cache: pnpm
+          cache-dependency-path: pnpm-lock.yaml
+      - name: Install locked dependencies
+        run: pnpm install --frozen-lockfile
+      - name: Verify lockfile unchanged
+        run: git diff --exit-code -- pnpm-lock.yaml
+      - name: Install tested browser and system dependencies
+        run: pnpm exec playwright install --with-deps ${{ matrix.browser }}
+      - name: Run the complete browser regression suite
+        env:
+          THROUGHLINE_QA_BROWSER: ${{ matrix.browser }}
+        run: pnpm test:browser:run
diff --git a/CHANGELOG.md b/CHANGELOG.md
index fb614f8..31f8369 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,10 @@ Semantic Versioning independently of the version-1 trace and program schemas.
 
 ## Unreleased
 
+### Fixed (cross-browser toolbar)
+
+- Keep the wide playback toolbar compact in WebKit without constraining native selector height; verify the compact bar still encloses every control across browser engines.
+
 ### Fixed (narration review)
 
 - Coordinate browser-global speech synthesis between multiple Throughline players; newer narration takes over while displaced players pause and stop owning cancellation.
diff --git a/src/react/__tests__/toolbar.browser.test.tsx b/src/react/__tests__/toolbar.browser.test.tsx
index 83791ee..20d0140 100644
--- a/src/react/__tests__/toolbar.browser.test.tsx
+++ b/src/react/__tests__/toolbar.browser.test.tsx
@@ -27,10 +27,23 @@ it("forms one aligned compact toolbar on wide screens and adapts by container wi
 	expect(Math.abs(centerY(chapter) - centerY(entity))).toBeLessThan(3);
 	expect(Math.abs(centerY(chapter) - centerY(play))).toBeLessThan(3);
 	expect(Math.abs(centerY(chapter) - centerY(timeline))).toBeLessThan(3);
-	expect(bottom.getBoundingClientRect().height).toBeLessThan(55);
+	const toolbarBounds = bottom.getBoundingClientRect();
+	expect(toolbarBounds.height).toBeLessThan(55);
+	// A compact bar must still enclose native form controls in every engine.
+	for (const control of bottom.querySelectorAll<HTMLElement>("button, select, input")) {
+		const rect = control.getBoundingClientRect();
+		const name = control.getAttribute("aria-label") ?? control.tagName;
+		expect(rect.top, name + " escapes toolbar top").toBeGreaterThanOrEqual(toolbarBounds.top - 1);
+		expect(rect.bottom, name + " escapes toolbar bottom").toBeLessThanOrEqual(toolbarBounds.bottom + 1);
+	}
 	expect(zoom.getBoundingClientRect().width).toBe(34);
 	expect(getComputedStyle(zoom.querySelector("svg")!).width).toBe("14px");
-	expect(chapter.getBoundingClientRect().height).toBe(34);
+	// Native select widgets are 34px in Chromium/Firefox and 42px in WebKit.
+	// Constrain the allowable size while the toolbar-height and bounds checks
+	// above enforce the actual compact, unclipped layout contract.
+	const chapterHeight = chapter.getBoundingClientRect().height;
+	expect(chapterHeight).toBeGreaterThanOrEqual(34);
+	expect(chapterHeight).toBeLessThanOrEqual(42);
 	expect(getComputedStyle(chapter).borderTopLeftRadius).toBe("2px");
 	expect(getComputedStyle(chapter).paddingLeft).toBe("8px");
 
diff --git a/src/styles/throughline.css b/src/styles/throughline.css
index 3960a22..e05a3b6 100644
--- a/src/styles/throughline.css
+++ b/src/styles/throughline.css
@@ -88,7 +88,8 @@
 	column-gap: 0.75rem;
 	row-gap: 0.375rem;
 	min-width: 0;
-	padding-block: 0.375rem;
+	/* Preserve native select height (notably WebKit) within the compact bar. */
+	padding-block: 0.25rem;
 	border-top: 1px solid var(--thl-line);
 	border-bottom: 1px solid var(--thl-line);
 }
diff --git a/vitest.browser.config.ts b/vitest.browser.config.ts
index c1e468d..ad34f2e 100644
--- a/vitest.browser.config.ts
+++ b/vitest.browser.config.ts
@@ -1,6 +1,14 @@
 import { playwright } from "@vitest/browser-playwright";
 import { defineConfig } from "vitest/config";
 
+// Main quality CI uses Chromium. The separate release QA workflow exercises
+// the identical browser suite in Firefox and WebKit without changing defaults.
+const requestedBrowser = process.env.THROUGHLINE_QA_BROWSER ?? "chromium";
+if (!["chromium", "firefox", "webkit"].includes(requestedBrowser)) {
+	throw new Error("Unsupported Throughline QA browser: " + requestedBrowser);
+}
+const browser = requestedBrowser as "chromium" | "firefox" | "webkit";
+
 export default defineConfig({
 	test: {
 		css: true,
@@ -9,7 +17,7 @@ export default defineConfig({
 		browser: {
 			enabled: true,
 			provider: playwright(),
-			instances: [{ browser: "chromium" }],
+			instances: [{ browser }],
 		},
 	},
 });