Added 404 page

assets/css/site.css

@@ -218,3 +218,22 @@ button:hover .icon svg {
     from {left: -300px; opacity: 0}
     to {left: 0; opacity: 1}
 }
+.logo-404 {
+    max-width: 200px;
+    max-height: 200px;
+    margin: 0 auto;
+    display: block;
+}
+.logo-404 svg {
+    max-width: 200px;
+    max-height: 200px;
+}
+.toc-404 {
+    max-width: 250px;
+    margin: 0 auto;
+}
+.message-404 {
+    font-size: 2em;
+    margin: 0 auto;
+    text-align: center;
+}

assets/templates/404.phtml

@@ -0,0 +1,11 @@
+<?php partial('header', ['title' => 'PHP Apprentice']) ?>
+
+<div class="container center">
+    <a href="/" class="logo-404"><?= icon('elephant') ?></a>
+    <p class="message-404">Whoops! The page could not be found.</p>
+    <div class="toc-404">
+        <?php partial('table_of_contents') ?>
+    </div>
+</div>
+
+<?php partial('footer') ?>