diff --git a/playwright.config.ts b/playwright.config.ts
index 8a9a4f28d..1ee341f56 100644
--- a/playwright.config.ts
+++ b/playwright.config.ts
@@ -33,6 +33,14 @@ export default defineConfig({
     trace: "retain-on-failure",
     screenshot: "only-on-failure",
     video: "retain-on-failure",
+    // HealthLog ships dark mode as the default (Dracula theme) — `globals.css`
+    // sets `color-scheme: dark` on the root and the `<ThemeProvider>` defaults
+    // to "system". Playwright's stock context is `colorScheme: "light"`, which
+    // means axe-core was scanning a layout users never actually see (Dracula
+    // greens on a light card → 1.18 contrast). Forcing the test theme to dark
+    // matches what real users render on first paint and is the only honest
+    // a11y baseline for this app.
+    colorScheme: "dark",
   },
 
   projects: [
@@ -41,6 +49,7 @@ export default defineConfig({
       use: {
         ...devices["Desktop Chrome"],
         viewport: { width: 1280, height: 720 },
+        colorScheme: "dark",
       },
     },
     {
@@ -51,6 +60,7 @@ export default defineConfig({
         // webkit. iPhone-13 is intentionally avoided here; the
         // mobile-Safari smoke is exercised by the iOS app suite.
         ...devices["Pixel 5"],
+        colorScheme: "dark",
       },
     },
   ],
diff --git a/src/components/admin/__tests__/user-management-responsive.test.tsx b/src/components/admin/__tests__/user-management-responsive.test.tsx
new file mode 100644
index 000000000..76837f560
--- /dev/null
+++ b/src/components/admin/__tests__/user-management-responsive.test.tsx
@@ -0,0 +1,128 @@
+import { describe, expect, it, vi } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+
+/**
+ * Phase A5 / B-mobile CRITICAL #2 — `/admin/users` mobile layout.
+ *
+ * The audit at 393 CSS px showed the desktop table (6 cols × N rows)
+ * truncating the role badge ("ADMI", "USE") and pushing the action
+ * column entirely off the right edge — the destructive force-logout
+ * action was unreachable on mobile.
+ *
+ * Fix: render the desktop table only at `≥ md`, and on `< md` paint
+ * a card-list (`<ul data-testid="admin-users-mobile-list">`) where
+ * every action button stays visible and tap-targetable.
+ *
+ * This test guards the responsive composition so a future refactor
+ * can't accidentally drop the mobile path.
+ */
+
+vi.mock("next/navigation", () => ({
+  useRouter: () => ({ push: vi.fn(), replace: vi.fn() }),
+  usePathname: () => "/admin/users",
+}));
+
+const sampleUsers = [
+  {
+    id: "u1",
+    username: "marc",
+    email: "marc@example.com",
+    role: "ADMIN" as const,
+    passkeyCount: 2,
+    createdAt: "2026-04-01T08:00:00Z",
+  },
+  {
+    id: "u2",
+    username: "alice",
+    email: null,
+    role: "USER" as const,
+    passkeyCount: 1,
+    createdAt: "2026-04-15T08:00:00Z",
+  },
+];
+
+vi.mock("@tanstack/react-query", () => ({
+  useQuery: () => ({ data: sampleUsers, isLoading: false }),
+  useQueryClient: () => ({ invalidateQueries: vi.fn() }),
+  useMutation: () => ({
+    mutate: vi.fn(),
+    mutateAsync: vi.fn(),
+    isPending: false,
+    isError: false,
+    error: null,
+  }),
+}));
+
+vi.mock("@/hooks/use-auth", () => ({
+  useAuth: () => ({
+    user: {
+      id: "u1",
+      username: "marc",
+      email: "marc@example.com",
+      role: "ADMIN",
+    },
+    isAuthenticated: true,
+    isLoading: false,
+    refetch: vi.fn(),
+  }),
+}));
+
+import { I18nProvider } from "@/lib/i18n/context";
+import { UserManagementSection } from "../user-management-section";
+
+function render() {
+  return renderToStaticMarkup(
+    <I18nProvider initialLocale="en">
+      <UserManagementSection />
+    </I18nProvider>,
+  );
+}
+
+describe("UserManagementSection — mobile responsive", () => {
+  it("hides the desktop table until md:", () => {
+    const html = render();
+    // The desktop table wrapper should carry `hidden md:block`.
+    expect(html).toMatch(/<div[^>]*\bhidden\b[^>]*\bmd:block\b/);
+  });
+
+  it("renders the mobile card-list at < md only", () => {
+    const html = render();
+    // The mobile list opts out at md+ via `md:hidden`.
+    expect(html).toContain('data-testid="admin-users-mobile-list"');
+    expect(html).toMatch(/<ul[^>]*\bmd:hidden\b/);
+  });
+
+  it("surfaces the role badge inside the mobile card (no truncation)", () => {
+    const html = render();
+    // ADMIN badge text appears at least twice — once in desktop table,
+    // once in the mobile card list. Both occurrences mean neither side
+    // accidentally lost the column.
+    const adminMatches = (html.match(/>ADMIN</g) ?? []).length;
+    expect(adminMatches).toBeGreaterThanOrEqual(2);
+  });
+
+  it("renders all four action buttons inside the mobile card", () => {
+    const html = render();
+    // Pull just the mobile-list section by splitting on its testid.
+    const mobileStart = html.indexOf('data-testid="admin-users-mobile-list"');
+    expect(mobileStart).toBeGreaterThan(0);
+    const mobileSlice = html.slice(mobileStart);
+    // Toggle role + edit + reset password + force-logout — four
+    // buttons. We probe their ARIA labels since the icons are
+    // identical-looking; the labels are the contract.
+    expect(mobileSlice).toContain("Edit user");
+    expect(mobileSlice).toContain("Reset password");
+    expect(mobileSlice).toContain("Force logout");
+  });
+
+  it("uses smaller card padding on mobile (p-4 sm:p-6)", () => {
+    const html = render();
+    expect(html).toMatch(/class="[^"]*\bp-4\b[^"]*sm:p-6/);
+  });
+
+  it("stacks header rows on mobile so filter pills don't collide with title", () => {
+    const html = render();
+    // Header carries `flex-col` at base + `sm:flex-row` at small+.
+    expect(html).toMatch(/class="[^"]*\bflex-col\b[^"]*sm:flex-row/);
+  });
+});
diff --git a/src/components/admin/user-management-section.tsx b/src/components/admin/user-management-section.tsx
index d88e58ae8..217985d61 100644
--- a/src/components/admin/user-management-section.tsx
+++ b/src/components/admin/user-management-section.tsx
@@ -153,9 +153,88 @@ export function UserManagementSection() {
     setResetMsg(null);
   }
 
+  /**
+   * Action buttons are reused for both the desktop-table (cramped) row
+   * and the mobile-card layout. Pulling them into a single helper keeps
+   * the two layouts in lock-step — when we add a new admin action we
+   * never have to remember to add it to both.
+   */
+  const renderUserActions = (u: AdminUser) => (
+    <>
+      <Button
+        variant="ghost"
+        size="sm"
+        className="min-h-11 min-w-11 px-3 text-xs"
+        onClick={() =>
+          updateUser.mutate({
+            id: u.id,
+            data: {
+              role: u.role === "ADMIN" ? "USER" : "ADMIN",
+            },
+          })
+        }
+        disabled={u.id === currentUserId}
+        title={
+          u.id === currentUserId
+            ? t("admin.ownRoleUnchangeable")
+            : u.role === "ADMIN"
+              ? t("admin.demoteToUser")
+              : t("admin.promoteToAdmin")
+        }
+      >
+        <Shield className="mr-1 h-3 w-3" aria-hidden="true" />
+        {u.role === "ADMIN" ? t("admin.toUser") : t("admin.toAdmin")}
+      </Button>
+      <Button
+        variant="ghost"
+        size="sm"
+        className="min-h-11 min-w-11 px-2 text-xs"
+        onClick={() => startEdit(u)}
+        title={t("admin.editUser")}
+        aria-label={t("admin.editUser")}
+      >
+        <Pencil className="h-3 w-3" aria-hidden="true" />
+      </Button>
+      <Button
+        variant="ghost"
+        size="sm"
+        className="min-h-11 min-w-11 px-2 text-xs"
+        onClick={() => startReset(u)}
+        title={t("admin.resetPassword")}
+        aria-label={t("admin.resetPassword")}
+      >
+        <KeyRound className="h-3 w-3" aria-hidden="true" />
+      </Button>
+      <Button
+        variant="ghost"
+        size="sm"
+        className="text-destructive hover:text-destructive min-h-11 min-w-11 px-2 text-xs"
+        onClick={() => setLogoutTarget(u)}
+        disabled={u.id === currentUserId}
+        title={
+          u.id === currentUserId
+            ? t("admin.section.users.cannotLogoutSelf")
+            : t("admin.section.users.forceLogout")
+        }
+        aria-label={
+          u.id === currentUserId
+            ? t("admin.section.users.cannotLogoutSelf")
+            : t("admin.section.users.forceLogout")
+        }
+      >
+        <LogOut className="h-3 w-3" aria-hidden="true" />
+      </Button>
+    </>
+  );
+
   return (
-    <div className="bg-card border-border rounded-xl border p-6">
-      <div className="flex items-center justify-between gap-2">
+    <div className="bg-card border-border rounded-xl border p-4 sm:p-6">
+      {/* Header: stacks vertically on mobile so the filter pills get
+          their own row instead of overlapping the title. The audit
+          flagged this as CRITICAL #2 — at 393px the filter row was
+          colliding with the count Badge and the user-count digit was
+          floating into the title's gap. */}
+      <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between sm:gap-2">
         <div className="flex items-center gap-2">
           <Users className="text-primary h-5 w-5" />
           <div className="text-lg font-semibold">
@@ -192,123 +271,107 @@ export function UserManagementSection() {
       </div>
 
       {filteredUsers ? (
-        <div className="mt-4 overflow-x-auto">
-          <table className="w-full text-sm">
-            <thead>
-              <tr className="text-muted-foreground border-b text-xs">
-                <th className="px-3 py-2 text-left font-medium">
-                  {t("admin.users")}
-                </th>
-                <th className="px-3 py-2 text-left font-medium">
-                  {t("admin.userEmail")}
-                </th>
-                <th className="px-3 py-2 text-center font-medium">
-                  {t("admin.userRole")}
-                </th>
-                <th className="px-3 py-2 text-center font-medium">
-                  {t("admin.userPasskeys")}
-                </th>
-                <th className="px-3 py-2 text-right font-medium">
-                  {t("admin.userCreated")}
-                </th>
-                <th className="px-3 py-2 text-right font-medium">
-                  {t("admin.userActions")}
-                </th>
-              </tr>
-            </thead>
-            <tbody className="divide-border divide-y">
-              {filteredUsers.map((u, i) => (
-                <tr key={u.id} className={i % 2 === 0 ? "bg-muted/30" : ""}>
-                  <td className="px-3 py-2 font-medium">{u.username}</td>
-                  <td className="text-muted-foreground px-3 py-2 text-xs">
-                    {u.email || "—"}
-                  </td>
-                  <td className="px-3 py-2 text-center">
-                    <Badge
-                      variant={u.role === "ADMIN" ? "default" : "secondary"}
-                      className="text-xs"
-                    >
-                      {u.role}
-                    </Badge>
-                  </td>
-                  <td className="px-3 py-2 text-center">{u.passkeyCount}</td>
-                  <td className="text-muted-foreground px-3 py-2 text-right text-xs whitespace-nowrap">
-                    {formatDate(u.createdAt)}
-                  </td>
-                  <td className="px-3 py-2 text-right">
-                    <div className="flex items-center justify-end gap-1">
-                      <Button
-                        variant="ghost"
-                        size="sm"
-                        className="min-h-11 min-w-11 px-3 text-xs"
-                        onClick={() =>
-                          updateUser.mutate({
-                            id: u.id,
-                            data: {
-                              role: u.role === "ADMIN" ? "USER" : "ADMIN",
-                            },
-                          })
-                        }
-                        disabled={u.id === currentUserId}
-                        title={
-                          u.id === currentUserId
-                            ? t("admin.ownRoleUnchangeable")
-                            : u.role === "ADMIN"
-                              ? t("admin.demoteToUser")
-                              : t("admin.promoteToAdmin")
-                        }
-                      >
-                        <Shield className="mr-1 h-3 w-3" aria-hidden="true" />
-                        {u.role === "ADMIN"
-                          ? t("admin.toUser")
-                          : t("admin.toAdmin")}
-                      </Button>
-                      <Button
-                        variant="ghost"
-                        size="sm"
-                        className="min-h-11 min-w-11 px-2 text-xs"
-                        onClick={() => startEdit(u)}
-                        title={t("admin.editUser")}
-                        aria-label={t("admin.editUser")}
-                      >
-                        <Pencil className="h-3 w-3" aria-hidden="true" />
-                      </Button>
-                      <Button
-                        variant="ghost"
-                        size="sm"
-                        className="min-h-11 min-w-11 px-2 text-xs"
-                        onClick={() => startReset(u)}
-                        title={t("admin.resetPassword")}
-                        aria-label={t("admin.resetPassword")}
-                      >
-                        <KeyRound className="h-3 w-3" aria-hidden="true" />
-                      </Button>
-                      <Button
-                        variant="ghost"
-                        size="sm"
-                        className="text-destructive hover:text-destructive min-h-11 min-w-11 px-2 text-xs"
-                        onClick={() => setLogoutTarget(u)}
-                        disabled={u.id === currentUserId}
-                        title={
-                          u.id === currentUserId
-                            ? t("admin.section.users.cannotLogoutSelf")
-                            : t("admin.section.users.forceLogout")
-                        }
-                        aria-label={
-                          u.id === currentUserId
-                            ? t("admin.section.users.cannotLogoutSelf")
-                            : t("admin.section.users.forceLogout")
-                        }
-                      >
-                        <LogOut className="h-3 w-3" aria-hidden="true" />
-                      </Button>
-                    </div>
-                  </td>
+        <>
+          {/* Desktop table: kept verbatim — only the wrapping
+              `md:block hidden` swaps it out for the card-list below at
+              `< md`. Hiding the table-only wrapper (instead of just
+              the cells) saves DOM weight on mobile too. */}
+          <div className="mt-4 hidden overflow-x-auto md:block">
+            <table className="w-full text-sm">
+              <thead>
+                <tr className="text-muted-foreground border-b text-xs">
+                  <th className="px-3 py-2 text-left font-medium">
+                    {t("admin.users")}
+                  </th>
+                  <th className="px-3 py-2 text-left font-medium">
+                    {t("admin.userEmail")}
+                  </th>
+                  <th className="px-3 py-2 text-center font-medium">
+                    {t("admin.userRole")}
+                  </th>
+                  <th className="px-3 py-2 text-center font-medium">
+                    {t("admin.userPasskeys")}
+                  </th>
+                  <th className="px-3 py-2 text-right font-medium">
+                    {t("admin.userCreated")}
+                  </th>
+                  <th className="px-3 py-2 text-right font-medium">
+                    {t("admin.userActions")}
+                  </th>
                 </tr>
-              ))}
-            </tbody>
-          </table>
-        </div>
+              </thead>
+              <tbody className="divide-border divide-y">
+                {filteredUsers.map((u, i) => (
+                  <tr key={u.id} className={i % 2 === 0 ? "bg-muted/30" : ""}>
+                    <td className="px-3 py-2 font-medium">{u.username}</td>
+                    <td className="text-muted-foreground px-3 py-2 text-xs">
+                      {u.email || "—"}
+                    </td>
+                    <td className="px-3 py-2 text-center">
+                      <Badge
+                        variant={u.role === "ADMIN" ? "default" : "secondary"}
+                        className="text-xs"
+                      >
+                        {u.role}
+                      </Badge>
+                    </td>
+                    <td className="px-3 py-2 text-center">
+                      {u.passkeyCount}
+                    </td>
+                    <td className="text-muted-foreground px-3 py-2 text-right text-xs whitespace-nowrap">
+                      {formatDate(u.createdAt)}
+                    </td>
+                    <td className="px-3 py-2 text-right">
+                      <div className="flex items-center justify-end gap-1">
+                        {renderUserActions(u)}
+                      </div>
+                    </td>
+                  </tr>
+                ))}
+              </tbody>
+            </table>
+          </div>
+
+          {/* Mobile card list: each user renders as a self-contained
+              card with the meta line + a flex-wrapping action row.
+              All four actions stay visible and tap-targetable; nothing
+              is hidden behind a horizontal scroll. */}
+          <ul
+            className="mt-4 space-y-2 md:hidden"
+            data-testid="admin-users-mobile-list"
+          >
+            {filteredUsers.map((u) => (
+              <li
+                key={u.id}
+                className="bg-muted/30 border-border rounded-lg border p-3"
+              >
+                <div className="flex items-start justify-between gap-2">
+                  <div className="min-w-0 flex-1">
+                    <div className="flex items-center gap-2">
+                      <span className="truncate font-medium">{u.username}</span>
+                      <Badge
+                        variant={u.role === "ADMIN" ? "default" : "secondary"}
+                        className="text-[10px]"
+                      >
+                        {u.role}
+                      </Badge>
+                    </div>
+                    <p className="text-muted-foreground truncate text-xs">
+                      {u.email || "—"}
+                    </p>
+                    <p className="text-muted-foreground text-[11px]">
+                      {t("admin.userPasskeys")}: {u.passkeyCount} ·{" "}
+                      {formatDate(u.createdAt)}
+                    </p>
+                  </div>
+                </div>
+                <div className="mt-2 flex flex-wrap items-center gap-1">
+                  {renderUserActions(u)}
+                </div>
+              </li>
+            ))}
+          </ul>
+        </>
       ) : (
         <div className="mt-4 flex items-center gap-2">
           <Loader2 className="text-muted-foreground h-4 w-4 animate-spin" />