diff --git a/webviews/src/pages/passwords/styles.css b/webviews/src/pages/passwords/styles.css
index 51031dc2deae..e9a8d2d14eb3 100644
--- a/webviews/src/pages/passwords/styles.css
+++ b/webviews/src/pages/passwords/styles.css
@@ -24,8 +24,14 @@
   min-width: 0;
 }
 
+/* In a narrow pane the actions wrap under the title, never over it or off the edge. */
+.pw-title-row {
+  flex-wrap: wrap;
+}
+
 .pw-title {
-  flex: 1;
+  flex: 1 0 auto;
+  max-width: 100%;
   min-width: 0;
   margin: 0;
   font-size: 20px;
@@ -35,11 +41,19 @@
   text-overflow: ellipsis;
 }
 
+/* One height for every control in the header's rows. */
+.pw-search,
+.pw-select,
+.pw-button {
+  box-sizing: border-box;
+  height: 28px;
+}
+
 .pw-search {
   flex: 1;
   min-width: 0;
   font-size: 15px;
-  padding: 6px 10px;
+  padding: 0 10px;
   border-radius: 7px;
   border: 1px solid var(--page-separator);
   background: transparent;
@@ -138,6 +152,14 @@
   border-radius: 6px;
 }
 
+/* A login keeps a readable username: in a narrow pane its badges, last-used and actions wrap under
+   it instead of squeezing it to one letter. Passkey and exception rows stay one line: their site
+   name ellipsizes. */
+.pw-site .pw-row {
+  flex-wrap: wrap;
+  row-gap: 2px;
+}
+
 .pw-row:hover {
   background: var(--page-hover);
 }
@@ -167,7 +189,7 @@
 }
 
 .pw-username {
-  flex: 1;
+  flex: 1 1 8em;
   min-width: 0;
   white-space: nowrap;
   overflow: hidden;
@@ -181,7 +203,7 @@
 
 .pw-username-form {
   display: flex;
-  flex: 1;
+  flex: 1 1 8em;
   min-width: 0;
   margin: 0;
 }
diff --git a/webviews/test/passwords-narrow.test.ts b/webviews/test/passwords-narrow.test.ts
new file mode 100644
index 000000000000..3921f4892b34
--- /dev/null
+++ b/webviews/test/passwords-narrow.test.ts
@@ -0,0 +1,106 @@
+// l10n-allow-file: test assertions on the page's English labels, not shipped UI.
+// The Passwords page in a narrow pane (a standalone 360 px pane, the gallery's narrow width): the
+// header's title and its actions all stay on screen (the actions wrap under the title rather than
+// pushing "Import from Browser" off the edge and the title to nothing), saved logins keep a readable
+// username (the badges, last-used and actions wrap under it) while passkey and exception rows stay
+// one line, and the controls in a header row share one height. At the normal width nothing wraps.
+//
+// Real Chromium from Playwright; CI fails the file when it cannot launch (requireBrowserLane).
+import { afterAll, beforeAll, describe, expect, setDefaultTimeout, test } from "bun:test";
+import path from "node:path";
+import { chromium, type Browser, type Page } from "playwright";
+import { requireBrowserLane } from "./support/requireBrowserLane";
+import { warmViteServer } from "./support/warmDevServer";
+
+await requireBrowserLane("passwords-narrow.test.ts", async () => {
+  setDefaultTimeout(120_000);
+  const { createServer } = await import("vite");
+  const webviews = path.resolve(import.meta.dir, "..");
+  const PAGE = "/src/pages/passwords/index.html?mock";
+  let vite: Awaited<ReturnType<typeof createServer>> | undefined;
+  let browser: Browser | undefined;
+  beforeAll(async () => {
+    vite = await createServer({
+      root: webviews,
+      configFile: path.join(webviews, "vite.config.ts"),
+      server: { port: 0, host: "127.0.0.1", strictPort: false },
+      logLevel: "error",
+    });
+    await vite.listen();
+    await warmViteServer(vite, PAGE);
+    browser = await chromium.launch({ headless: true });
+  });
+  afterAll(async () => {
+    await browser?.close();
+    await vite?.close();
+  });
+
+  async function open(width: number): Promise<Page> {
+    const { port } = vite!.httpServer!.address() as { port: number };
+    const page = await browser!.newPage({ viewport: { width, height: 720 } });
+    await page.goto(`http://127.0.0.1:${port}${PAGE}`);
+    await page.locator(".pw-site .pw-row .pw-username").first().waitFor();
+    return page;
+  }
+
+  const measure = (page: Page) =>
+    page.evaluate(() => {
+      const box = (element: Element) => element.getBoundingClientRect();
+      const header = box(document.querySelector(".pw-header")!);
+      const title = document.querySelector<HTMLElement>(".pw-title")!;
+      const titleRow = [...document.querySelectorAll(".pw-title-row > *")].map(box);
+      const searchRow = [...document.querySelectorAll(".pw-search-row > *")].map(box);
+      const rows = [...document.querySelectorAll(".pw-site .pw-row")].map((row) => {
+        const name = row.querySelector<HTMLElement>(".pw-username")!;
+        const actions = box(row.querySelector(".pw-actions")!);
+        return { name: box(name).width, wants: name.scrollWidth, nameTop: box(name).top, actionsTop: actions.top };
+      });
+      return {
+        header: { left: header.left, right: header.right },
+        title: { shown: title.clientWidth, wants: title.scrollWidth },
+        titleRow: {
+          right: Math.max(...titleRow.map((b) => b.right)),
+          lines: new Set(titleRow.map((b) => Math.round(b.top + b.height / 2))).size,
+        },
+        searchHeights: searchRow.map((b) => Math.round(b.height)),
+        rows,
+      };
+    });
+
+  describe("passwords page", () => {
+    test("at 360 px the header and the saved logins fit the pane", async () => {
+      const page = await open(360);
+      const m = await measure(page);
+      // Passkey and exception rows stay one line with a long site name: badge, name and actions.
+      const oneLine = await page.evaluate(() =>
+        [...document.querySelectorAll(".pw-section .pw-row")]
+          .filter((row) => !row.closest(".pw-site"))
+          .map((row) => {
+            row.querySelector(".pw-site-name")!.textContent = "accounts.login.very-long-subdomain.example-bank.co.uk";
+            const middles = [".pw-site-badge", ".pw-site-name", ".pw-actions"].map((selector) => {
+              const box = row.querySelector(selector)!.getBoundingClientRect();
+              return box.top + box.height / 2;
+            });
+            // The spread of their middles: under 8 px is one line (a wrapped item sits a row lower).
+            return Math.max(...middles) - Math.min(...middles);
+          }),
+      );
+      await page.close();
+      expect(oneLine.length).toBeGreaterThan(0);
+      for (const spread of oneLine) expect(spread).toBeLessThan(8);
+      expect(m.title.shown).toBeGreaterThanOrEqual(m.title.wants);
+      expect(m.titleRow.right).toBeLessThanOrEqual(360);
+      for (const row of m.rows) expect(row.name).toBeGreaterThanOrEqual(Math.min(row.wants, 96));
+      expect(new Set(m.searchHeights).size).toBe(1);
+    });
+
+    test("at 900 px the header and every login stay on one line", async () => {
+      const page = await open(900);
+      const m = await measure(page);
+      await page.close();
+      expect(m.titleRow.lines).toBe(1);
+      for (const row of m.rows) expect(Math.abs(row.nameTop - row.actionsTop)).toBeLessThan(8);
+      expect(new Set(m.searchHeights).size).toBe(1);
+    });
+  });
+});