diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 2b06429..56fa24d 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -1284,9 +1284,14 @@ function template_preprocess_image(&$variables) {
   $variables['attributes']['src'] = file_create_url($variables['uri']);
 
   foreach (array('width', 'height', 'alt', 'title') as $key) {
+    // If there is a value for the variable, it overrides the attribute.
     if (isset($variables[$key])) {
       $variables['attributes'][$key] = $variables[$key];
     }
+    // Otherwise, remove the attribute.
+    else {
+      unset($variables['attributes'][$key]);
+    }
   }
 }
 
diff --git a/core/modules/book/config/install/node.type.book.yml b/core/modules/book/config/install/node.type.book.yml
index e7ad5f7..b226112 100644
--- a/core/modules/book/config/install/node.type.book.yml
+++ b/core/modules/book/config/install/node.type.book.yml
@@ -1,7 +1,7 @@
 type: book
 name: 'Book page'
 description: '<em>Books</em> have a built-in hierarchical navigation. Use for handbooks or tutorials.'
-help: ''
+help: 'Add content here organized in a hierarchy.'
 has_title: true
 title_label: Title
 settings:
diff --git a/core/modules/node/src/NodeForm.php b/core/modules/node/src/NodeForm.php
index 0c5bbc6..17b3799 100644
--- a/core/modules/node/src/NodeForm.php
+++ b/core/modules/node/src/NodeForm.php
@@ -69,6 +69,9 @@ public function form(array $form, array &$form_state) {
     // name in 'TYPE-node-form' potentially clashes with third-party class
     // names.
     $form['#attributes']['class'][0] = drupal_html_class('node-' . $node->getType() . '-form');
+    if (isset($form['help'])) {
+      $form['#attributes']['aria-describedby'] = 'block-bartik-help';
+    }
 
     // Changed must be sent to the client, for later overwrite error checking.
     $form['changed'] = array(
diff --git a/core/profiles/standard/config/install/node.type.article.yml b/core/profiles/standard/config/install/node.type.article.yml
index 2c58ec6..a57e059 100644
--- a/core/profiles/standard/config/install/node.type.article.yml
+++ b/core/profiles/standard/config/install/node.type.article.yml
@@ -1,7 +1,7 @@
 type: article
 name: Article
 description: 'Use <em>articles</em> for time-sensitive content like news, press releases or blog posts.'
-help: ''
+help: 'Add time-sensitive content here.'
 has_title: true
 title_label: Title
 settings:
diff --git a/core/profiles/standard/config/install/node.type.page.yml b/core/profiles/standard/config/install/node.type.page.yml
index f72d0c6..fe10af3 100644
--- a/core/profiles/standard/config/install/node.type.page.yml
+++ b/core/profiles/standard/config/install/node.type.page.yml
@@ -1,7 +1,7 @@
 type: page
 name: 'Basic page'
 description: 'Use <em>basic pages</em> for your static content, such as an ''About us'' page.'
-help: ''
+help: 'Add static content here.'
 has_title: true
 title_label: Title
 settings: