v3: lots of small UI tweaks and fixes

src/App.tsx

@@ -62,6 +62,9 @@ const ResetPassword = lazy(() =>
     default: m.ResetPassword,
   }))
 );
+const NotFound = lazy(() =>
+  import("./pages/NotFound.tsx").then((m) => ({ default: m.NotFound }))
+);
 
 function AppRoutes() {
   return (
@@ -111,6 +114,7 @@ function AppRoutes() {
             </RestrictedLoggedIn>
           }
         />
+        <Route path="*" element={<NotFound />} />
       </Routes>
     </Suspense>
   );