diff --git a/www/.php/format.inc b/www/.php/format.inc
index 495890a..6f0c3e7 100644
--- a/www/.php/format.inc
+++ b/www/.php/format.inc
@@ -40,9 +40,9 @@ function _get_fmt(): string {
     $type = sizeof($fmts) > 0 ? array_key_first($fmts) : null;
     if (str_contains($type, '/json')) {
         return 'json';
-    } else if ($type === 'text/html') {
-        return 'html';
-    } else {
+    } else if ($type === 'text/plain') {
         return 'text';
+    } else {
+        return 'html';
     }
 }
diff --git a/www/clients.php b/www/clients.php
index 9c44b69..be5c781 100644
--- a/www/clients.php
+++ b/www/clients.php
@@ -104,10 +104,11 @@ if ($path == '') {
 <html xmlns="http://www.w3.org/1999/xhtml" lang="de-AT">
 <head>
   <meta charset="UTF-8"/>
-  <title>Mandanten - Elwig - Elektronische Winzergenossenschaftsverwaltung</title>
+  <title>Mandanten - Elwig</title>
+  <meta name="description" content="Elektronische Winzergenossenschaftsverwaltung"/>
   <link rel="icon" href="/favicon.ico" sizes="16x16 20x20 24x24 30x30 32x32 36x36 40x40 48x48 60x60 64x64 72x72 80x80 96x96 128x128 256x256"/>
   <link rel="stylesheet" href="/res/style.css"/>
-  <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
+  <meta name="viewport" content="width=device-width,initial-scale=1.0"/>
 </head>
 <body>
   <main>
diff --git a/www/files/index.php b/www/files/index.php
index 2c349dc..f63a751 100644
--- a/www/files/index.php
+++ b/www/files/index.php
@@ -117,13 +117,30 @@ if ($format === 'json') {
     header('Content-Type: application/xhtml+xml; charset=UTF-8');
     echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
     ?>
-<html xmlns="http://www.w3.org/1999/xhtml" lang="de-AT">
+<html xmlns="http://www.w3.org/1999/xhtml" lang="de-AT" prefix="og: https://ogp.me/ns#">
 <head>
   <meta charset="UTF-8"/>
-  <title>Downloads - Elwig - Elektronische Winzergenossenschaftsverwaltung</title>
+  <title>Downloads - Elwig</title>
+  <meta name="description" content="Elektronische Winzergenossenschaftsverwaltung"/>
   <link rel="icon" href="/favicon.ico" sizes="16x16 20x20 24x24 30x30 32x32 36x36 40x40 48x48 60x60 64x64 72x72 80x80 96x96 128x128 256x256"/>
   <link rel="stylesheet" href="/res/style.css"/>
-  <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
+  <meta name="viewport" content="width=device-width,initial-scale=1.0"/>
+  <meta name="theme-color" content="#A040C0"/>
+  <meta name="mobile-web-app-capable" content="yes"/>
+  <meta name="apple-mobile-web-app-capable" content="yes"/>
+  <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent"/>
+  <meta property="og:site_name" content="Elwig"/>
+  <meta property="og:title" content="Downloads - Elwig"/>
+  <meta property="og:description" content="Elektronische Winzergenossenschaftsverwaltung"/>
+  <meta property="og:type" content="website"/>
+  <meta property="og:url" content="https://elwig.at/files/"/>
+  <meta property="og:image" content="https://elwig.at/res/images/preview.jpg"/>
+  <meta property="og:image:type" content="image/jpeg"/>
+  <meta property="og:image:width" content="1200"/>
+  <meta property="og:image:height" content="630"/>
+  <meta property="og:locale" content="de_AT"/>
+  <meta property="og:ttl" content="60"/>
+  <meta name="twitter:card" content="summary_large_image"/>
 </head>
 <body>
   <main>
diff --git a/www/index.xhtml b/www/index.xhtml
index e930d5b..d7dce9d 100644
--- a/www/index.xhtml
+++ b/www/index.xhtml
@@ -1,11 +1,28 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<html xmlns="http://www.w3.org/1999/xhtml" lang="de-AT">
+<html xmlns="http://www.w3.org/1999/xhtml" lang="de-AT" prefix="og: https://ogp.me/ns#">
 <head>
   <meta charset="UTF-8"/>
-  <title>Elwig - Elektronische Winzergenossenschaftsverwaltung</title>
+  <title>Elwig</title>
+  <meta name="description" content="Elektronische Winzergenossenschaftsverwaltung"/>
   <link rel="icon" href="/favicon.ico" sizes="16x16 20x20 24x24 30x30 32x32 36x36 40x40 48x48 60x60 64x64 72x72 80x80 96x96 128x128 256x256"/>
   <link rel="stylesheet" href="/res/style.css"/>
-  <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
+  <meta name="viewport" content="width=device-width,initial-scale=1.0"/>
+  <meta name="theme-color" content="#A040C0"/>
+  <meta name="mobile-web-app-capable" content="yes"/>
+  <meta name="apple-mobile-web-app-capable" content="yes"/>
+  <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent"/>
+  <meta property="og:site_name" content="Elwig"/>
+  <meta property="og:title" content="Elwig"/>
+  <meta property="og:description" content="Elektronische Winzergenossenschaftsverwaltung"/>
+  <meta property="og:type" content="website"/>
+  <meta property="og:url" content="https://elwig.at/"/>
+  <meta property="og:image" content="https://elwig.at/res/images/preview.jpg"/>
+  <meta property="og:image:type" content="image/jpeg"/>
+  <meta property="og:image:width" content="1200"/>
+  <meta property="og:image:height" content="630"/>
+  <meta property="og:locale" content="de_AT"/>
+  <meta property="og:ttl" content="60"/>
+  <meta name="twitter:card" content="summary_large_image"/>
 </head>
 <body style="margin-top: 3em;">
   <header>
diff --git a/www/res/images/preview.jpg b/www/res/images/preview.jpg
new file mode 100644
index 0000000..54962fb
Binary files /dev/null and b/www/res/images/preview.jpg differ
diff --git a/www/robots.txt b/www/robots.txt
new file mode 100644
index 0000000..391d3a7
--- /dev/null
+++ b/www/robots.txt
@@ -0,0 +1,4 @@
+# robots.txt for elwig.at
+User-Agent: *
+Disallow: /clients/
+Sitemap: https://elwig.at/sitemap.xml
diff --git a/www/sitemap.xml b/www/sitemap.xml
new file mode 100644
index 0000000..9bdf704
--- /dev/null
+++ b/www/sitemap.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="https://www.sitemaps.org/schemas/sitemap/0.9">
+  <url>
+    <loc>https://elwig.at/</loc>
+    <changefreq>monthly</changefreq>
+    <priority>1.0</priority>
+  </url>
+  <url>
+    <loc>https://elwig.at/files/</loc>
+    <changefreq>monthly</changefreq>
+    <priority>0.5</priority>
+  </url>
+</urlset>