diff --git a/source/includes/_footer.html.erb b/source/includes/_footer.html.erb
index a777937..d445d73 100644
--- a/source/includes/_footer.html.erb
+++ b/source/includes/_footer.html.erb
@@ -3,7 +3,7 @@
 <footer class='row footer'>
   <div class="container-fluid">
     <div class='col-12 col-sm-6 col-md-3 '>
-      <h4>About Us</h4>
+      <h2>About Us</h2>
       <ul>
       <% data.links.about_links.each do |link| %>
         <li><%= link_to link.name, link.url %></a></li>
@@ -11,7 +11,7 @@
       </ul>
     </div>
     <div class='col-12 col-sm-6 col-md-3'>
-      <h4>Work With Us</h4>
+      <h2>Work With Us</h2>
       <ul>
       <% data.links.services_links.each do |link| %>
         <li><%= link_to link.name, link.url %></a></li>
@@ -20,7 +20,7 @@
     </div>
     <div class="clearfix visible-sm"></div>
     <div class='col-12 col-sm-6 col-md-3'>
-      <h4>Membership</h4>
+      <h2>Membership</h2>
       <ul>
       <% data.links.community_links.each do |link| %>
         <li><%= link_to link.name, link.url %></a></li>
@@ -28,7 +28,7 @@
       </ul>
     </div>
     <div class='col-12 col-sm-6 col-md-3'>
-      <h4>Resources</h4>
+      <h2>Resources</h2>
       <ul>
       <% data.links.resources_links.each do |link| %>
         <li><%= link_to link.name, link.url %></a></li>
@@ -40,24 +40,24 @@
     <div class="col-md-12">
       <div class="contact">
         <div class="socials">
-          <% link_to 'mailto:support@datacite.org', class: "share" do %>
-            <i class='fas fa-envelope'></i>
+          <% link_to 'mailto:support@datacite.org', class: "share", "aria-label": "Email DataCite support" do %>
+            <i class='fas fa-envelope' aria-hidden="true"></i>
           <% end %>
-          <% link_to 'https://datacite.org/blog/', class: "share" do %>
-            <i class='fas fa-blog'></i>
+          <% link_to 'https://datacite.org/blog/', class: "share", "aria-label": "DataCite blog" do %>
+            <i class='fas fa-blog' aria-hidden="true"></i>
           <% end %>
-          <% link_to 'https://github.com/datacite/datacite', class: "share" do %>
-            <i class='fab fa-github'></i>
+          <% link_to 'https://github.com/datacite/datacite', class: "share", "aria-label": "DataCite on GitHub" do %>
+            <i class='fab fa-github' aria-hidden="true"></i>
           <% end %>
-          <% link_to 'https://twitter.com/datacite', class: "share" do %>
-            <svg xmlns="http://www.w3.org/2000/svg" height="1em" viewBox="0 0 512 512" style="fill: #a3acb2;position: relative;bottom: -3;"><!--! Font Awesome Free 6.4.2 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license (Commercial License) Copyright 2023 Fonticons, Inc. --><path d="M389.2 48h70.6L305.6 224.2 487 464H345L233.7 318.6 106.5 464H35.8L200.7 275.5 26.8 48H172.4L272.9 180.9 389.2 48zM364.4 421.8h39.1L151.1 88h-42L364.4 421.8z"></path></svg>
+          <% link_to 'https://twitter.com/datacite', class: "share", "aria-label": "DataCite on X" do %>
+            <svg xmlns="http://www.w3.org/2000/svg" height="1em" viewBox="0 0 512 512" style="fill: #a3acb2;position: relative;bottom: -3;" aria-hidden="true" focusable="false"><!--! Font Awesome Free 6.4.2 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license (Commercial License) Copyright 2023 Fonticons, Inc. --><path d="M389.2 48h70.6L305.6 224.2 487 464H345L233.7 318.6 106.5 464H35.8L200.7 275.5 26.8 48H172.4L272.9 180.9 389.2 48zM364.4 421.8h39.1L151.1 88h-42L364.4 421.8z"></path></svg>
           <% end %>
-          <a rel="me" class="share" href="https://openbiblio.social/@datacite"><i class='fab fa-mastodon'></i></a>
-          <% link_to 'https://www.linkedin.com/company/datacite', class: "share" do %>
-            <i class='fab fa-linkedin'></i>
+          <a rel="me" class="share" href="https://openbiblio.social/@datacite" aria-label="DataCite on Mastodon"><i class='fab fa-mastodon' aria-hidden="true"></i></a>
+          <% link_to 'https://www.linkedin.com/company/datacite', class: "share", "aria-label": "DataCite on LinkedIn" do %>
+            <i class='fab fa-linkedin' aria-hidden="true"></i>
           <% end %>
-          <% link_to 'https://www.youtube.com/@DataCiteChannel', class: "share" do %>
-            <i class='fab fa-youtube'></i>
+          <% link_to 'https://www.youtube.com/@DataCiteChannel', class: "share", "aria-label": "DataCite on YouTube" do %>
+            <i class='fab fa-youtube' aria-hidden="true"></i>
           <% end %>
         </div>
         <ul class="share">
diff --git a/source/includes/_header.html.erb b/source/includes/_header.html.erb
index 8d07de0..f973183 100644
--- a/source/includes/_header.html.erb
+++ b/source/includes/_header.html.erb
@@ -18,7 +18,7 @@
         <span class="icon-bar"></span>
       </button>
       <a class="navbar-brand" id="navbar-brand-fix" href="/">
-        <img src="/images/DataCite-Metadata-Schema-logo_bicolor-light-sm.svg" title="<%= ENV['SITE_TITLE'] %>" style="height:100%;">
+        <img src="/images/DataCite-Metadata-Schema-logo_bicolor-light-sm.svg" title="<%= ENV['SITE_TITLE'] %>" alt="<%= ENV['SITE_TITLE'] %>" style="height:100%;">
       </a>
     </div>
     <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
diff --git a/source/layouts/index.erb b/source/layouts/index.erb
index 3d399cf..deac2f8 100644
--- a/source/layouts/index.erb
+++ b/source/layouts/index.erb
@@ -12,11 +12,11 @@
       <div class='col-md-3'>
         <div class="panel facets">
           <div class="panel-body">
-            <h4>Schema Versions</h4>
+            <h2>Schema Versions</h4>
             <ul>
               <% data.schemas.each do |schema| %>
                 <li class="schema">
-                  <h5><%= link_to schema.title, "/meta/kernel-#{schema.version}" %></h5>
+                  <h3><%= link_to schema.title, "/meta/kernel-#{schema.version}" %></h5>
                   <%= schema.date.strftime("%-d %b %Y") %>
                 </li>
               <% end %>
diff --git a/source/layouts/layout.erb b/source/layouts/layout.erb
index 0a519af..f5ed712 100644
--- a/source/layouts/layout.erb
+++ b/source/layouts/layout.erb
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-  <html>
+  <html lang="en">
     <head>
     <meta charset="utf-8">
     <!-- (1) Optimize for mobile versions: http://goo.gl/EOpFl -->
@@ -201,6 +201,13 @@
         .navbar .navbar-nav > li > a {
             margin-top: 5px;
             margin-bottom: 5px;
+            min-width: 44px;
+            min-height: 44px;
+            display: inline-flex;
+            align-items: center;
+        }
+        .navbar .navbar-nav > li {
+            margin-bottom: 4px;
         }
         .navbar .navbar-brand {
             margin: 0px;
@@ -339,13 +346,14 @@
         
         .footer a,
         .footer a:visited,
-        .footer h4 {
+        .footer h2 {
             color: #ccc;
             font-size: 14px;
         }
         
-        .footer h4 {
+        .footer h2 {
             color: #fff;
+            margin: 1.33em 0;
         }
         
         .navbar-default .navbar-nav > li > a:not(.btn):focus,
@@ -420,6 +428,12 @@
         
         .footer .socials a {
             margin-right: 15px;
+            margin-right: 15px;
+            min-width: 44px;
+            min-height: 44px;
+            display: inline-flex;
+            align-items: center;
+            justify-content: center;
         }
         
         .footer .share {
@@ -603,7 +617,9 @@
   </head>
   <body>
     <%= partial "includes/header.html.erb" %>
+    <main id="main-content">
     <%= yield %>
+    </main>
     <%= partial "includes/footer.html.erb" %>
     <%= partial "includes/javascripts.html.erb" %>
   </body>
diff --git a/source/meta/kernel-4.7/index.html.md b/source/meta/kernel-4.7/index.html.md
index ca2e61e..581d4b9 100644
--- a/source/meta/kernel-4.7/index.html.md
+++ b/source/meta/kernel-4.7/index.html.md
@@ -21,7 +21,7 @@ DataCite Metadata Working Group. (2026). DataCite Metadata Schema for the Public
 
 ## Changes
 
-#### See [Version 4.7 Update](https://datacite-metadata-schema.readthedocs.io/en/4.7/introduction/version-update) for full details.
+### See [Version 4.7 Update](https://datacite-metadata-schema.readthedocs.io/en/4.7/introduction/version-update) for full details.
 
 
 * Addition of new resourceTypeGeneral values: Poster and Presentation
diff --git a/source/meta/kernel-4/index.html.md b/source/meta/kernel-4/index.html.md
index ca2e61e..581d4b9 100644
--- a/source/meta/kernel-4/index.html.md
+++ b/source/meta/kernel-4/index.html.md
@@ -21,7 +21,7 @@ DataCite Metadata Working Group. (2026). DataCite Metadata Schema for the Public
 
 ## Changes
 
-#### See [Version 4.7 Update](https://datacite-metadata-schema.readthedocs.io/en/4.7/introduction/version-update) for full details.
+### See [Version 4.7 Update](https://datacite-metadata-schema.readthedocs.io/en/4.7/introduction/version-update) for full details.
 
 
 * Addition of new resourceTypeGeneral values: Poster and Presentation