Add 451 page and prettify the 404 page

config/apache/standardebooks.org.conf

@@ -78,6 +78,7 @@ Define webroot /standardebooks.org/web
 	ServerAlias		www.${domain}
 	DocumentRoot		${webroot}/www
 	ErrorDocument		404	/404
+	ErrorDocument		451	/451
 	ErrorLog		/var/log/local/www-error.log
 	DirectorySlash		Off
 	RewriteEngine		on

config/apache/standardebooks.test.conf

@@ -61,6 +61,7 @@ Define webroot /standardebooks.org/web
 	ServerAlias		www.${domain}
 	DocumentRoot		${webroot}/www
 	ErrorDocument		404	/404
+	ErrorDocument		451	/451
 	ErrorLog		/var/log/local/www-error.log
 	DirectorySlash		Off
 	RewriteEngine		on

www/404.php

@@ -1,7 +1,21 @@
 <?
 require_once('Core.php');
-?><?= Template::Header(['title' => 'We couldn’t find that document', 'description' => 'We couldn’t find that document.']) ?>
-<main class="center">
-	<h1>We couldn’t find that document.</h1>
+
+?><?= Template::Header(['title' => 'We Couldn’t Find That Document', 'highlight' => '', 'description' => 'We couldn’t find that document.']) ?>
+<main>
+	<section class="narrow has-hero">
+		<hgroup>
+			<h1>We Couldn’t Find That Document</h1>
+			<h2>This is 404 error.</h2>
+		</hgroup>
+		<picture data-caption="Blind Orion Searching for the Rising Sun. Nicolas Poussin, 1658">
+			<source srcset="/images/blind-orion@2x.avif 2x, /images/blind-orion.avif 1x" type="image/avif"/>
+			<source srcset="/images/blind-orion@2x.jpg 2x, /images/blind-orion.jpg 1x" type="image/jpg"/>
+			<img src="/images/blind-orion@2x.jpg" alt="A classical city is aflame as people scramble in the foreground."/>
+		</picture>
+		<p>We couldn’t find a document at the URL you specified. Did you mistype the URL?</p>
+		<p>If you arrived here from a link on the Standard Ebooks website, please <a href="/about#editor-in-chief">contact us</a> so that we can fix it.</p>
+		<p>If you arrived here from a link elsewhere on the web, please contact the site you came from to ask them to fix their link.</p>
+	</section>
 </main>
 <?= Template::Footer() ?>

www/451.php

@@ -0,0 +1,19 @@
+<?
+require_once('Core.php');
+
+?><?= Template::Header(['title' => 'This Ebook Is No Longer Available', 'highlight' => '', 'description' => 'This ebook is unavailable due to legal reasons.']) ?>
+<main>
+	<section class="narrow has-hero">
+		<hgroup>
+			<h1>This Ebook Is No Longer Available</h1>
+			<h2>This is 451 error.</h2>
+		</hgroup>
+		<picture data-caption="The Course of Empire: Destruction. Thomas Cole, 1836">
+			<source srcset="/images/the-course-of-empire-destruction@2x.avif 2x, /images/the-course-of-empire-destruction.avif 1x" type="image/avif"/>
+			<source srcset="/images/the-course-of-empire-destruction@2x.jpg 2x, /images/the-course-of-empire-destruction.jpg 1x" type="image/jpg"/>
+			<img src="/images/the-course-of-empire-destruction@2x.jpg" alt="A classical city is aflame as people scramble in the foreground."/>
+		</picture>
+		<p>This ebook is no longer available, due to legal reasons. This may occur if the book was erroneously thought to be in the U.S. public domain, but new evidence changed that determination.</p>
+	</section>
+</main>
+<?= Template::Footer() ?>