diff --git a/.env.example b/.env.example
index 445e928..b913a3c 100644
--- a/.env.example
+++ b/.env.example
@@ -1,2 +1,2 @@
 PORT=3000
-NEXT_PUBLIC_API_URL=https://cms.ggcamp.org
\ No newline at end of file
+NEXT_PUBLIC_API_URL=https://www.hailearning.edu.vn/
\ No newline at end of file
diff --git a/app/not-found.tsx b/app/not-found.tsx
new file mode 100644
index 0000000..d73b1db
--- /dev/null
+++ b/app/not-found.tsx
@@ -0,0 +1,55 @@
+import Link from "next/link";
+
+export default function NotFound() {
+  return (
+    <>
+      <section
+        className="breadcrumb-wrapper fix bg-cover"
+        style={{
+          backgroundImage: "url(/assets/img/inner-page/breadcrumb.jpg)",
+        }}
+      >
+        <div className="shape">
+          <img src="/assets/img/inner-page/shape.png" alt="img" />
+        </div>
+        <div className="container">
+          <div className="page-heading">
+            <h1 className="breadcrumb-title">Page Not Found</h1>
+            <ul className="breadcrumb-list">
+              <li>
+                <Link href="/">Home</Link>
+              </li>
+              <li>
+                <i className="fa-solid fa-chevron-right"></i>
+              </li>
+              <li>
+                <a href="#">Not Found</a>
+              </li>
+            </ul>
+          </div>
+        </div>
+      </section>
+
+      <section className="section-padding">
+        <div className="container">
+          <div className="row justify-content-center">
+            <div className="col-lg-8 text-center">
+              <div className="error-content">
+                <h2 className="mb-3">404 - Page Not Found</h2>
+                <p className="mb-4">
+                  The page you're looking for could not be found. It may have been moved or deleted. Please check the URL or return to the home page.
+                </p>
+                <div className="button-group">
+                  <Link href="/" className="theme-btn">
+                    Back to Home
+                    <i className="fa-solid fa-arrow-right"></i>
+                  </Link>
+                </div>
+              </div>
+            </div>
+          </div>
+        </div>
+      </section>
+    </>
+  );
+}
diff --git a/pages/[level]/[slug]/index.tsx b/pages/[level]/[slug]/index.tsx
deleted file mode 100644
index f0cc077..0000000
--- a/pages/[level]/[slug]/index.tsx
+++ /dev/null
@@ -1,14 +0,0 @@
-import { useRouter } from "next/router";
-
-export default function LevelSlugPage() {
-  const router = useRouter();
-  const { level, slug } = router.query;
-
-  return (
-    <div style={{ padding: 20 }}>
-      <h1>Lesson page</h1>
-      <p>Level: {level}</p>
-      <p>Slug: {slug}</p>
-    </div>
-  );
-}
diff --git a/pages/[level]/index.tsx b/pages/[level]/index.tsx
deleted file mode 100644
index e9d07b9..0000000
--- a/pages/[level]/index.tsx
+++ /dev/null
@@ -1,13 +0,0 @@
-import { useRouter } from "next/router";
-
-export default function LevelPage() {
-  const router = useRouter();
-  const { level } = router.query;
-
-  return (
-    <div style={{ padding: 20 }}>
-      <h1>Level page</h1>
-      <p>Level: {level}</p>
-    </div>
-  );
-}
diff --git a/pages/_app.tsx b/pages/_app.tsx
deleted file mode 100644
index 86d8929..0000000
--- a/pages/_app.tsx
+++ /dev/null
@@ -1,6 +0,0 @@
-import type { AppProps } from "next/app";
-import "../app/globals.css";
-
-export default function MyApp({ Component, pageProps }: AppProps) {
-  return <Component {...pageProps} />;
-}
diff --git a/pages/_document.tsx b/pages/_document.tsx
deleted file mode 100644
index b2fff8b..0000000
--- a/pages/_document.tsx
+++ /dev/null
@@ -1,13 +0,0 @@
-import { Html, Head, Main, NextScript } from "next/document";
-
-export default function Document() {
-  return (
-    <Html lang="en">
-      <Head />
-      <body>
-        <Main />
-        <NextScript />
-      </body>
-    </Html>
-  );
-}
