diff --git a/tests/integration/online-board/start-page.test.tsx b/tests/integration/online-board/start-page.test.tsx
index 11a3cee7..709e9990 100644
--- a/tests/integration/online-board/start-page.test.tsx
+++ b/tests/integration/online-board/start-page.test.tsx
@@ -65,6 +65,30 @@ vi.mock("@/ui/city-autocomplete/index.js", () => ({
 describe("Start page integration", () => {
   beforeEach(() => {
     vi.clearAllMocks();
+
+    // Stub matchMedia for useIsMobileViewport (jsdom doesn't implement it).
+    Object.defineProperty(window, "matchMedia", {
+      value: vi.fn().mockImplementation((query: string) => ({
+        matches: false,
+        media: query,
+        addEventListener: () => {},
+        removeEventListener: () => {},
+        dispatchEvent: () => false,
+      })),
+      configurable: true,
+    });
+
+    // Stub geolocation for useGeoCityDefault (jsdom doesn't implement it).
+    Object.defineProperty(navigator, "geolocation", {
+      value: {
+        getCurrentPosition: vi.fn().mockImplementation(
+          (_s: PositionCallback, onErr: PositionErrorCallback) => {
+            onErr({ code: 1, message: "denied" } as GeolocationPositionError);
+          },
+        ),
+      },
+      configurable: true,
+    });
   });
 
   it("renders the page layout with data-testid", () => {