Add initial 404 page

i18n/en.yaml

@@ -11,3 +11,13 @@
 # Footer
 - id: footer_credits
   translation: "Powered by <a href=\"https://gohugo.io/\" rel=\"nofollow noopener\" target=\"_blank\">Hugo</a> and <a href=\"https://github.com/vimux/binario\" rel=\"nofollow noopener\" target=\"_blank\">Binario</a> theme."
+
+# 404
+- id: page404_title
+  translation: "404 Page not found"
+
+- id: page404_lead
+  translation: "Sorry, the page you were looking for doesn't exist."
+
+- id: page404_link
+  translation: "Go back to main page"

layouts/404.html

@@ -0,0 +1,9 @@
+{{ partial "header.html" . }}
+<div class="main">
+	<div class="page404 block center">
+		<h1 class="page404__title">{{ T "page404_title" }}</h1>
+		<p class="page404__lead">{{ T "page404_lead" }}</p>
+		<a class="page404__link" href="">{{ T "page404_link" }}</a>
+	</div>
+</div>
+{{ partial "footer.html" . }}

static/css/main.css

@@ -725,6 +725,21 @@ mark {
 	border-color: #888;
 }
 
+/* 404 */
+.page404__title {
+	font-size: 2.25rem;
+	font-weight: 700;
+}
+
+.page404__lead {
+	font-size: 1.5rem;
+	margin-bottom: 2rem;
+}
+
+.page404__link {
+	font-size: 1.5rem;
+}
+
 /* Footer */
 .footer {
 	padding: .625rem 0;