diff --git a/doxyconfig-header.html b/doxyconfig-header.html
index 174eaf6..4f680d4 100644
--- a/doxyconfig-header.html
+++ b/doxyconfig-header.html
@@ -1,4 +1,4 @@
-<!-- HTML header for doxygen 1.10.0-->
+<!-- HTML header for doxygen 1.18.0-->
 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 <html xmlns="http://www.w3.org/1999/xhtml" lang="$langISO">
 <head>
@@ -8,19 +8,36 @@
 <meta name="viewport" content="width=device-width, initial-scale=1"/>
 <!--BEGIN PROJECT_NAME--><title>$projectname: $title</title><!--END PROJECT_NAME-->
 <!--BEGIN !PROJECT_NAME--><title>$title</title><!--END !PROJECT_NAME-->
+<!--BEGIN PROJECT_ICON-->
 <link rel="icon" href="$relpath^$projecticon" type="image/x-icon" />
+<!--END PROJECT_ICON-->
 <link href="$relpath^tabs.css" rel="stylesheet" type="text/css"/>
-<!--BEGIN DISABLE_INDEX-->
 <!--BEGIN FULL_SIDEBAR-->
-<script type="text/javascript">var page_layout=1;</script>
+<meta name="doxygen-page-layout" content="1" />
 <!--END FULL_SIDEBAR-->
-<!--END DISABLE_INDEX-->
-<script type="text/javascript" src="$relpath^jquery.js"></script>
+<!--BEGIN HTML_DYNAMIC_SECTIONS-->
 <script type="text/javascript" src="$relpath^dynsections.js"></script>
+<!--END HTML_DYNAMIC_SECTIONS-->
+<!--BEGIN HTML_CODE_FOLDING-->
+<script type="text/javascript" src="$relpath^codefolding.js"></script>
+<!--END HTML_CODE_FOLDING-->
+<!--BEGIN COPY_CLIPBOARD-->
+<script type="text/javascript" src="$relpath^clipboard.js"></script>
+<!--END COPY_CLIPBOARD-->
 $treeview
+<script type="text/javascript">
+  if (typeof Cookie !== 'undefined') {
+    // Read the Docs projects share one origin, so isolate Doxygen's generic
+    // settings to the current project and version directory.
+    const docsPath = new URL('$relpath^.', location.href).pathname
+      .replace(/[^A-Za-z0-9_-]/g, '_')
+    Cookie.cookie_namespace += `${docsPath}_`
+  }
+</script>
 $search
 $mathjax
 $darkmode
+$mermaidjs
 <link href="$relpath^$stylesheet" rel="stylesheet" type="text/css" />
 $extrastylesheet
 
@@ -55,11 +72,18 @@
 <!--DOXYGEN-AWESOME END-->
 </head>
 <body>
-<!--BEGIN DISABLE_INDEX-->
-  <!--BEGIN FULL_SIDEBAR-->
+<script type="text/javascript">
+  // Doxygen 1.18's external search runtime expects this element on every page.
+  if (!location.pathname.endsWith('/search.html')) {
+    const searchResults = document.createElement('div')
+    searchResults.id = 'searchresults'
+    searchResults.hidden = true
+    document.body.appendChild(searchResults)
+  }
+</script>
+<!--BEGIN FULL_SIDEBAR-->
 <div id="side-nav" class="ui-resizable side-nav-resizable"><!-- do not remove this div, it is closed by doxygen! -->
-  <!--END FULL_SIDEBAR-->
-<!--END DISABLE_INDEX-->
+<!--END FULL_SIDEBAR-->
 
 <div id="top"><!-- do not remove this div, it is closed by doxygen! -->
 
