added test + 404 page

Author: Jannik-Hm

404.html

@@ -0,0 +1,25 @@
+---
+permalink: /404.html
+layout: default
+---
+
+<style type="text/css" media="screen">
+  .container {
+    margin: 10px auto;
+    max-width: 600px;
+    text-align: center;
+  }
+  h1 {
+    margin: 30px 0;
+    font-size: 4em;
+    line-height: 1;
+    letter-spacing: -1px;
+  }
+</style>
+
+<div class="container">
+  <h1>404</h1>
+
+  <p><strong>Page not found :(</strong></p>
+  <p>The requested page could not be found.</p>
+</div>

index.md

@@ -0,0 +1,7 @@
+---
+# Feel free to add content and custom Front Matter to this file.
+# To modify the layout, see https://jekyllrb.com/docs/themes/#overriding-theme-defaults
+
+layout: default
+---
+# This is a Test page