feat: not found page updated

frontend/src/components/PageNotFound.tsx

@@ -3,12 +3,14 @@ import Header from './Header';
 export const PageNotFound = () => {
   return (
     <>
-      <Header />
-      <div>
-        Page not found
+      <Header/>
+      <div className="flex h-[90vh] justify-center">
+        <span className="mt-10 text-3xl">
+          <b>Page not found</b>
+        </span>
       </div>
     </>
-  )
-}
+  );
+};
 
 export default PageNotFound;