Fix 404.html with Jekyll front matter and SPA redirect workaround

Author: devnomadic

404.html

@@ -0,0 +1,39 @@
+---
+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>
+
+  <script type="text/javascript">
+    // GitHub Pages SPA redirect workaround
+    var pathSegmentsToKeep = 0; // Set to 0 for default github.io domains
+    
+    var l = window.location;
+    l.replace(
+      l.protocol + '//' + l.hostname + (l.port ? ':' + l.port : '') +
+      l.pathname.split('/').slice(0, 1 + pathSegmentsToKeep).join('/') + '/?/' +
+      l.pathname.slice(1).split('/').slice(pathSegmentsToKeep).join('/').replace(/&/g, '~and~') +
+      (l.search ? '&' + l.search.slice(1).replace(/&/g, '~and~') : '') +
+      l.hash
+    );
+  </script>
+</div>