MAESTRO: Fix 320px overflow and add responsive check

Auto Run Docs/SpecKit-web-header-analyzer-Phase-09-Polish.md

@@ -40,7 +40,7 @@ This phase performs final integration, accessibility audit, responsive testing,
 - [x] `npx prettier --check src/` — zero errors. Notes: ran `npx prettier --check src/` in `frontend/` (all matched files formatted).
 - [x] No `any` types in TypeScript
 - [x] WCAG 2.1 AA compliant (ARIA labels, keyboard nav, contrast ratios). Notes: reviewed interactive components for ARIA labels/roles, keyboard activation handlers, and focus-visible styles; contrast tokens align with >=60% text opacity and highlighted error states.
-- [ ] Responsive at 320px, 768px, 1024px, 1440px, 2560px — no layout issues
+- [x] Responsive at 320px, 768px, 1024px, 1440px, 2560px — no layout issues. Notes: added Playwright breakpoint overflow checks in `frontend/e2e/responsive.spec.ts`, set `min-w-0` on page columns and test selector groups to stop 320px overflow; ran `npx playwright test e2e/responsive.spec.ts --project=chromium`.
 - [ ] Lighthouse score ≥90 on Slow 4G preset
 - [ ] Analysis completes within 10s for sample headers
 - [ ] README.md updated with web interface documentation

frontend/e2e/responsive.spec.ts

@@ -0,0 +1,56 @@
+import { test, expect } from "@playwright/test";
+import fs from "fs/promises";
+import path from "path";
+
+const headersPath = path.resolve(__dirname, "../../backend/tests/fixtures/sample_headers.txt");
+
+const viewports = [
+  { width: 320, height: 900, label: "320" },
+  { width: 768, height: 900, label: "768" },
+  { width: 1024, height: 900, label: "1024" },
+  { width: 1440, height: 900, label: "1440" },
+  { width: 2560, height: 1200, label: "2560" },
+];
+
+test("responsive layout has no horizontal overflow at key breakpoints", async ({ page }) => {
+  const headers = await fs.readFile(headersPath, "utf8");
+
+  await page.goto("http://localhost:3100");
+
+  const headerInput = page.getByRole("textbox", { name: "Header Input" });
+  await headerInput.fill(headers);
+
+  await page.getByRole("button", { name: "Analyse Headers" }).click();
+
+  const reportContainer = page.getByTestId("report-container");
+  await reportContainer.waitFor({ state: "visible", timeout: 30000 });
+
+  for (const viewport of viewports) {
+    await page.setViewportSize({ width: viewport.width, height: viewport.height });
+    await page.waitForTimeout(200);
+
+    const metrics = await page.evaluate(() => {
+      const docEl = document.documentElement;
+      const body = document.body;
+      return {
+        docScrollWidth: docEl.scrollWidth,
+        docClientWidth: docEl.clientWidth,
+        bodyScrollWidth: body.scrollWidth,
+        bodyClientWidth: body.clientWidth,
+      };
+    });
+
+    expect(
+      metrics.docScrollWidth,
+      `documentElement overflow at ${viewport.label}px width`,
+    ).toBeLessThanOrEqual(metrics.docClientWidth);
+
+    expect(
+      metrics.bodyScrollWidth,
+      `body overflow at ${viewport.label}px width`,
+    ).toBeLessThanOrEqual(metrics.bodyClientWidth);
+
+    await expect(headerInput).toBeVisible();
+    await expect(reportContainer).toBeVisible();
+  }
+});

frontend/src/app/page.tsx

@@ -159,12 +159,12 @@ export default function Home() {
           </header>
 
           <section className="grid gap-6 lg:grid-cols-[2fr_1fr]">
-            <div className="flex flex-col gap-6">
+            <div className="flex min-w-0 flex-col gap-6">
               <HeaderInput value={headerInput} onChange={setHeaderInput} />
               <AnalysisControls config={analysisConfig} onChange={setAnalysisConfig} />
             </div>
 
-            <div className="flex flex-col gap-6">
+            <div className="flex min-w-0 flex-col gap-6">
               <FileDropZone onFileContent={setHeaderInput} />
 
               <div className="rounded-2xl border border-info/10 bg-surface p-6">

frontend/src/components/TestSelector.tsx

@@ -187,15 +187,15 @@ export default function TestSelector({ selectedTestIds, onSelectionChange }: Tes
             </p>
           ) : null}
 
-          <div className="grid gap-4">
+          <div className="grid min-w-0 gap-4">
             {groupedTests.map((group) => (
               <div
                 key={group.category}
-                className="rounded-xl border border-info/10 bg-background/40 p-4"
+                className="w-full min-w-0 rounded-xl border border-info/10 bg-background/40 p-4"
               >
-                <div className="flex items-center justify-between text-xs uppercase tracking-[0.2em] text-info/80">
-                  <span>{group.category}</span>
-                  <span className="font-mono text-[10px] text-text/50">
+                <div className="flex flex-wrap items-center justify-between gap-2 text-xs uppercase tracking-[0.2em] text-info/80">
+                  <span className="min-w-0 break-words">{group.category}</span>
+                  <span className="min-w-0 font-mono text-[10px] text-text/50">
                     {group.tests.length} tests
                   </span>
                 </div>
@@ -203,7 +203,7 @@ export default function TestSelector({ selectedTestIds, onSelectionChange }: Tes
                   {group.tests.map((test) => (
                     <label
                       key={test.id}
-                      className="flex items-start gap-3 rounded-lg border border-info/10 bg-surface/40 p-3 text-sm text-text/80"
+                      className="flex min-w-0 items-start gap-3 rounded-lg border border-info/10 bg-surface/40 p-3 text-sm text-text/80"
                     >
                       <input
                         type="checkbox"
@@ -213,8 +213,8 @@ export default function TestSelector({ selectedTestIds, onSelectionChange }: Tes
                         data-testid={`test-checkbox-${test.id}`}
                         aria-label={test.name}
                       />
-                      <span className="flex flex-col gap-1">
-                        <span className="font-medium">{test.name}</span>
+                      <span className="min-w-0 flex flex-col gap-1">
+                        <span className="break-words font-medium">{test.name}</span>
                         <span className="font-mono text-[10px] text-text/50">ID {test.id}</span>
                       </span>
                     </label>