diff --git a/content/pages/articles.njk b/content/pages/articles.njk
index d11c34c..0539ab2 100644
--- a/content/pages/articles.njk
+++ b/content/pages/articles.njk
@@ -1,8 +1,9 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.w3.org/MarkUp/SCHEMA/xhtml11.xsd" xml:lang="en">
+<!DOCTYPE html>
+<html lang="en">
+
 <head>
     {% include "templates/defaultTags.njk" %}
-    <link rel="stylesheet" type="text/css" href="/assets/css/sitemap.css" />
+    <link rel="stylesheet" type="text/css" href="/assets/css/sitemap.css">
     <title>Site Map</title>
 </head>
 <body>
diff --git a/content/pages/articles/graphical-profile/colours.njk b/content/pages/articles/graphical-profile/colours.njk
index 5f7378b..7628c2d 100644
--- a/content/pages/articles/graphical-profile/colours.njk
+++ b/content/pages/articles/graphical-profile/colours.njk
@@ -3,7 +3,7 @@
 {% import "components/color.njk" as color with context %}
 
 {% block head %}
-    <link rel="stylesheet" type="text/css" href="/assets/css/graphical-profile.css" />
+    <link rel="stylesheet" type="text/css" href="/assets/css/graphical-profile.css">
     <title>qwik - colours</title>
 {% endblock %}
 
diff --git a/content/pages/index.njk b/content/pages/index.njk
index 27b251a..045d0f0 100644
--- a/content/pages/index.njk
+++ b/content/pages/index.njk
@@ -1,13 +1,14 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.w3.org/MarkUp/SCHEMA/xhtml11.xsd" xml:lang="en">
+<!DOCTYPE html>
+<html lang="en">
+
 <head>
     {% include "templates/defaultTags.njk" %}
-    <link rel="stylesheet" type="text/css" href="/assets/css/landing.css" />
+    <link rel="stylesheet" type="text/css" href="/assets/css/landing.css">
     <title>qwik</title>
 </head>
 <body>
     <div id="header">
-        <img class="logo" src="/assets/images/logo.svg" alt="qwik logo" />
+        <img class="logo" src="/assets/images/logo.svg" alt="qwik logo">
         <h1>
             Welcome to <span style="color: var(--primary)">qwik</span><span style="color: var(--accent)">.</span><span style="color: var(--primary)">space</span>!
         </h1>
diff --git a/content/templates/article.njk b/content/templates/article.njk
index 227e102..679b8ac 100644
--- a/content/templates/article.njk
+++ b/content/templates/article.njk
@@ -1,9 +1,10 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.w3.org/MarkUp/SCHEMA/xhtml11.xsd" xml:lang="en">
+<!DOCTYPE html>
+<html lang="en">
+
 <head>
     {% include "./defaultTags.njk" %}
-    <link rel="stylesheet" href="/assets/css/article.css" />
-    <link rel="stylesheet" href="/assets/css/syntax.css" />
+    <link rel="stylesheet" href="/assets/css/article.css">
+    <link rel="stylesheet" href="/assets/css/syntax.css">
     {% block head %}
         <title>{{ serverName }}</title>
     {% endblock %}
diff --git a/content/templates/article_md.njk b/content/templates/article_md.njk
index b71d9f4..168f894 100644
--- a/content/templates/article_md.njk
+++ b/content/templates/article_md.njk
@@ -1,9 +1,10 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.w3.org/MarkUp/SCHEMA/xhtml11.xsd" xml:lang="en">
+<!DOCTYPE html>
+<html lang="en">
+
 <head>
     {% include "./defaultTags.njk" %}
-    <link rel="stylesheet" href="/assets/css/article.css" />
-    <link rel="stylesheet" href="/assets/css/syntax.css" />
+    <link rel="stylesheet" href="/assets/css/article.css">
+    <link rel="stylesheet" href="/assets/css/syntax.css">
     {% block head %}
         <title>{{ serverName }}</title>
     {% endblock %}
diff --git a/content/templates/defaultTags.njk b/content/templates/defaultTags.njk
index 8e86a15..bade31f 100644
--- a/content/templates/defaultTags.njk
+++ b/content/templates/defaultTags.njk
@@ -1,17 +1,17 @@
-<meta http-equiv="Content-Type" content="application/xhtml+xml;charset=utf-8" />
-<meta name="viewport" content="width=device-width, initial-scale=1.0" />
+<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1.0">
 
-<link rel="apple-touch-icon" sizes="180x180" href="/assets/favicons/apple-touch-icon.png" />
-<link rel="icon" type="image/png" sizes="32x32" href="/assets/favicons/favicon-32x32.png" />
-<link rel="icon" type="image/png" sizes="16x16" href="/assets/favicons/favicon-16x16.png" />
-<link rel="manifest" href="/assets/favicons/site.webmanifest" />
-<link rel="mask-icon" href="/assets/favicons/safari-pinned-tab.svg" color="#3ddf89" />
-<link rel="shortcut icon" href="/assets/favicons/favicon.ico" />
-<meta name="msapplication-TileColor" content="#181833" />
-<meta name="msapplication-config" content="/assets/favicons/browserconfig.xml" />
-<meta name="theme-color" content="#3ddf89" />
+<link rel="apple-touch-icon" sizes="180x180" href="/assets/favicons/apple-touch-icon.png">
+<link rel="icon" type="image/png" sizes="32x32" href="/assets/favicons/favicon-32x32.png">
+<link rel="icon" type="image/png" sizes="16x16" href="/assets/favicons/favicon-16x16.png">
+<link rel="manifest" href="/assets/favicons/site.webmanifest">
+<link rel="mask-icon" href="/assets/favicons/safari-pinned-tab.svg" color="#3ddf89">
+<link rel="shortcut icon" href="/assets/favicons/favicon.ico">
+<meta name="msapplication-TileColor" content="#181833">
+<meta name="msapplication-config" content="/assets/favicons/browserconfig.xml">
+<meta name="theme-color" content="#3ddf89">
 
-<link rel="stylesheet" type="text/css" href="/assets/css/scaling.css" />
-<link rel="stylesheet" type="text/css" href="/assets/css/colors.css" />
-<link rel="stylesheet" type="text/css" href="/assets/css/fonts.css" />
-<link rel="stylesheet" type="text/css" href="/assets/css/theme.css" />
+<link rel="stylesheet" type="text/css" href="/assets/css/scaling.css">
+<link rel="stylesheet" type="text/css" href="/assets/css/colors.css">
+<link rel="stylesheet" type="text/css" href="/assets/css/fonts.css">
+<link rel="stylesheet" type="text/css" href="/assets/css/theme.css">
diff --git a/content/templates/external_md.njk b/content/templates/external_md.njk
index 761a93c..e304b20 100644
--- a/content/templates/external_md.njk
+++ b/content/templates/external_md.njk
@@ -1,9 +1,10 @@
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.w3.org/MarkUp/SCHEMA/xhtml11.xsd" xml:lang="en">
+<!DOCTYPE html>
+<html lang="en">
+
 <head>
     {% include "templates/defaultTags.njk" %}
-    <link rel="stylesheet" href="/assets/css/article.css" />
-    <link rel="stylesheet" href="/assets/css/syntax.css" />
+    <link rel="stylesheet" href="/assets/css/article.css">
+    <link rel="stylesheet" href="/assets/css/syntax.css">
     <title>{{ externalMeta.title if externalMeta.title else serverName }}</title>
 </head>
 <body>
diff --git a/libs/nunjucksConfig.js b/libs/nunjucksConfig.js
index 3c4b173..1d39f65 100644
--- a/libs/nunjucksConfig.js
+++ b/libs/nunjucksConfig.js
@@ -1,5 +1,5 @@
 import njkMarkdown from 'nunjucks-markdown'
-import marked from 'marked'
+import { marked } from 'marked'
 
 import { markedRenderer } from './markedRenderer.js'
 import { utils } from './utils/utils.js'
@@ -24,7 +24,9 @@ export function nunjacksConfig(njk, express, Config) {
     marked.use({
         gfm: true,                  // Use GitHub formatting?
         renderer: markedRenderer,   // Use my own custom rendering for som tags
-        xhtml: true                 // Use XHTML for extra GAINZ!
+        mangle: false,              // Remove deprecated warning 
+        headerIds: false,           // Remove deprecated warning
+        headerPrefix: false         // Remove deprecated warning
     })
 
     // Let nunjucks use markdown.
diff --git a/package.json b/package.json
index 59cb01a..f7979e7 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,7 @@
     "express": "^4.17.1",
     "highlight.js": "^11.2.0",
     "jsdom": "^16.7.0",
-    "marked": "^2.1.3",
+    "marked": "^6.0.0",
     "nunjucks": "^3.2.3",
     "nunjucks-markdown": "^2.0.1"
   }
