Remove trailing slashes from URLs

source/.htaccess

@@ -0,0 +1,15 @@
+Options +FollowSymLinks -MultiViews
+
+RewriteEngine on
+
+# Remove trailing slashes from directories.
+DirectorySlash Off
+RewriteCond %{REQUEST_FILENAME} -d
+RewriteCond %{REQUEST_URI} !/$
+RewriteCond %{REQUEST_FILENAME}/index.html -f
+RewriteRule (.*) $1/index.html [L]
+RewriteRule ^(.*)/$ /$1 [L,R=301]
+
+# Remove index.html from URLs.
+RewriteCond %{THE_REQUEST} \s/+(.*/)?index\.html[\s?] [NC]
+RewriteRule ^(.*)index\.html$ /$1 [L,R=301]

source/_includes/zets/related.html.twig

@@ -5,7 +5,7 @@
     <ul>
       {% for zet in zets if related|filter((title) => title == zet.title) %}
         <li>
-          <a href="{{ zet.url }}">{{ zet.title }}</a>
+          <a href="{{ zet.url|trim('/', 'right') }}">{{ zet.title }}</a>
         </li>
       {% endfor %}
     </ul>

source/index.html.twig

@@ -7,7 +7,7 @@ use: [zets]
 <ul>
   {% for zet in data.zets %}
     <li>
-      <a href="{{ zet.url }}">
+      <a href="{{ zet.url|trim('/', 'right') }}">
         {{- zet.date|date }}: {{ zet.title -}}
       </a>
     </li>