Add 404.astro page

src/pages/404.astro

@@ -0,0 +1,20 @@
+---
+import Layout from "~/layouts/Empty.astro";
+---
+
+<Layout>
+    <main>
+        <section class="flex items-center h-full p-16">
+            <div class="container flex flex-col items-center justify-center px-5 mx-auto my-8">
+                <div class="max-w-md text-center">
+                    <h2 class="mb-8 font-extrabold text-9xl bg-clip-text text-transparent bg-gradient-to-r from-blue-500 to-pink-500 whitespace-nowrap">
+                        <span class="sr-only">Error</span>404
+                    </h2>
+                    <p class="text-3xl font-semibold md:text-3xl">Sorry, we couldn't find this page.</p>
+                    <p class="mt-4 mb-8 text-lg text-gray-600 dark:text-slate-400">But dont worry, you can find plenty of other things on our homepage.</p>
+                    <a rel="noopener noreferrer" href="./" class="btn text-white bg-gray-900 hover:bg-gray-800 dark:bg-gray-700 dark:hover:bg-gray-800 ml-4">Back to homepage</a>
+                </div>
+            </div>
+        </section>
+    </main>
+</Layout>