diff --git a/frontend/e2e/responsive-i18n.spec.ts b/frontend/e2e/responsive-i18n.spec.ts
new file mode 100644
index 0000000..65b9c44
--- /dev/null
+++ b/frontend/e2e/responsive-i18n.spec.ts
@@ -0,0 +1,57 @@
+import { expect, test, type APIRequestContext } from "@playwright/test";
+
+async function resetDemoData(request: APIRequestContext) {
+  await request.post("/api/v1/demo/login", { data: { role: "operations_manager" } });
+  await request.post("/api/v1/demo/reset");
+}
+
+// Cross-checks the responsive shell across the exact breakpoint matrix from the polish
+// brief (1440x1000, 1280x800, 1024x768, 768x1024, 430x932, 390x844, 360x800) in all three
+// supported languages -- both that nothing overflows horizontally and that the localized
+// heading text still renders (rather than being silently truncated away).
+const BREAKPOINTS: { width: number; height: number }[] = [
+  { width: 1440, height: 1000 },
+  { width: 1280, height: 800 },
+  { width: 1024, height: 768 },
+  { width: 768, height: 1024 },
+  { width: 430, height: 932 },
+  { width: 390, height: 844 },
+  { width: 360, height: 800 },
+];
+
+const LANGUAGES: { code: string; attentionTitle: string }[] = [
+  { code: "nl-BE", attentionTitle: "Aandachtspunten" },
+  { code: "en-GB", attentionTitle: "Attention queue" },
+  { code: "fr-BE", attentionTitle: "File d'attention" },
+];
+
+test.beforeEach(async ({ request }) => {
+  await resetDemoData(request);
+});
+
+for (const language of LANGUAGES) {
+  test.describe(`${language.code}`, () => {
+    for (const bp of BREAKPOINTS) {
+      test(`no horizontal overflow at ${bp.width}x${bp.height}`, async ({ page }) => {
+        await page.addInitScript(
+          (lang) => localStorage.setItem("fleetops.language", lang),
+          language.code,
+        );
+        await page.setViewportSize({ width: bp.width, height: bp.height });
+        await page.goto("/login");
+        await page.getByRole("button", { name: /begeleide demo|guided demo|démo guidée/i }).click();
+        await expect(page).toHaveURL(/\/dashboard/);
+
+        await expect(page.getByRole("heading", { name: language.attentionTitle })).toBeVisible();
+
+        const dimensions = await page.evaluate(() => ({
+          scroll: document.documentElement.scrollWidth,
+          client: document.documentElement.clientWidth,
+        }));
+        expect(dimensions.scroll, `${language.code} @ ${bp.width}x${bp.height}`).toBeLessThanOrEqual(
+          dimensions.client + 1,
+        );
+      });
+    }
+  });
+}
diff --git a/frontend/src/styles.css b/frontend/src/styles.css
index e2556dd..ee64c2f 100644
--- a/frontend/src/styles.css
+++ b/frontend/src/styles.css
@@ -427,6 +427,6 @@ details summary { cursor: pointer; color: var(--teal-dark); }.data-table details
   .tabs { margin-inline: -2px; }.record-surface { padding: 10px; }.detail-grid { grid-template-columns: 1fr 1fr; }.detail-grid div { min-height: 70px; padding: 11px; }.return-progress { padding-inline: 12px; gap: 6px; }.return-progress b { width: 20px; }.return-progress span { font-size: .58rem; }.return-form > .section-heading { padding: 16px; }.return-capture, .return-review { padding: 16px; }.form-grid, .condition-fieldset, .review-facts { grid-template-columns: 1fr; }.condition-fieldset { display: grid; }.review-facts div { display: flex; justify-content: space-between; align-items: center; }.review-facts dd { margin: 0; }.form-actions { padding: 12px 16px; }.form-actions .button { flex: 1; }.duplicate-compare { padding: 14px; }.duplicate-compare fieldset label { display: flex !important; margin-bottom: 8px; }.integration-cards article { min-height: 140px; }.knowledge-input-row { align-items: stretch; }.knowledge-input-row .button { min-width: 72px; padding-inline: 10px; }.knowledge-empty { min-height: 250px; padding: 22px 16px; }.retrieval-flow { width: 100%; gap: 4px; }.retrieval-flow span { padding: 5px; font-size: .52rem; }.retrieval-flow i { flex: 1; min-width: 5px; }.login-story { min-height: 38vh; }.login-message > p:last-child { font-size: .8rem; }.control-illustration { display: none; }.login-access { min-height: 62vh; padding: 34px 20px 50px; }.login-options button { min-height: 72px; }.app-footer { display: none; }
 }
 
-@media (max-width: 420px) {
+@media (max-width: 440px) {
   .global-search input::placeholder { color: transparent; }.global-search { max-width: 118px; }.topbar-meta { margin-left: auto; }.demo-guide-trigger { display: none; }.avatar { width: 29px; height: 29px; }.mobile-nav a span, .mobile-nav button span { max-width: 56px; overflow: hidden; text-overflow: ellipsis; }.filters { grid-template-columns: 1fr; }.filters label:first-child { grid-column: auto; }.detail-grid { grid-template-columns: 1fr; }.readiness-metrics { margin-right: -1px; }.badge { font-size: .55rem; }.page-header h1 { font-size: 1.5rem; }.login-message h1 { font-size: 2.6rem; }
 }