diff --git a/source b/source
index 42bad96967f..06dd8ff0922 100644
--- a/source
+++ b/source
@@ -2084,8 +2084,8 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
     <p>Applications and tools that process HTML and XML documents for reasons other than to either
     render the documents or check them for conformance should act in accordance with the semantics
     of the documents that they process.</p>
-	
-	<p class="example">A tool that generates document outlines but increases the nesting level for
+
+     <p class="example">A tool that generates document outlines but increases the nesting level for
     each paragraph and does not increase the nesting level for <span
     data-x="concept-heading">headings</span> would not be conforming.</p>
    </dd>
@@ -17066,7 +17066,6 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
    <p>Authors might prefer the former style for its terseness, or the latter style for its
    convenience in the face of heavy editing; which is best is purely an issue of preferred authoring
    style.</p>
-  
  </div>
 
 
@@ -17080,7 +17079,7 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
    <dd>Where <span>heading content</span> is expected.</dd>
    <dt><span data-x="concept-element-content-model">Content model</span>:</dt>
    <dd>One <code>h1</code>, <code>h2</code>, <code>h3</code>, <code>h4</code>,
-   <code>h5</code>, <code>h6</code> element, optionally with one or more <code>p</code> elements, 
+   <code>h5</code>, <code>h6</code> element, optionally with one or more <code>p</code> elements,
   optionally intermixed with <span>script-supporting elements</span>.</dd>
    <dt><span data-x="concept-element-attributes">Content attributes</span>:</dt>
    <dd><span>Global attributes</span></dd>
@@ -17092,13 +17091,14 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
    <dd>Uses <code>HTMLElement</code>.</dd>
   </dl>
 
-  <p>The <code>hgroup</code> element has no special meaning at all. It <span>represents</span> its children. 
- The element may be used to group a <code>h1</code>&ndash;<code>h6</code> element, for styling purposes, 
- with one or more <code>p</code> elements containing text representing its subheading, alternative title, or tagline.</p>
+  <p>The <code>hgroup</code> element <span>represents</span> its children. It otherwise has no
+ special meaning at all. The element may be used to group <code>h1</code>&ndash;<code>h6</code>
+ elements, for styling purposes, with one or more <code>p</code> elements containing text
+ representing its subheading, alternative title, or tagline.</p>
 
   <div class="example">
 
-   <p>Here are some examples of valid headings contained within a <code>hgroup</code> element.</p>
+   <p>Here are some examples of valid headings contained within an <code>hgroup</code> element.</p>
 
     <pre><code class="html">&lt;hgroup&gt;
  &lt;h1&gt;The reality dysfunction&lt;/h1&gt;
@@ -17475,20 +17475,19 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
 
  <h4><dfn>Headings and sections</dfn></h4>
 
-  <p><span>Heading content</span> elements have a <dfn>heading level</dfn>, which is 
-  an unsigned integer. It is determined as follows for a given <span>heading content</span> element
+  <p><span>Heading content</span> elements have a <dfn>heading level</dfn>, which is an unsigned
+  integer. It is determined as follows for a given <span>heading content</span> element
   <var>heading</var>:</p>
 
   <ol>
-  
    <li>
     <p>Switch on <var>heading</var>:</p>
 
     <dl class="switch">
-	 <dt><code>h1</code></dt>
+     <dt><code>h1</code></dt>
      <dd>Return 1.</dd>
-     
-	 <dt><code>h2</code></dt>
+
+     <dt><code>h2</code></dt>
      <dd>Return 2.</dd>
 
      <dt><code>h3</code></dt>
@@ -17504,12 +17503,12 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
      <dd>Return 6.</dd>
     </dl>
    </li>
-   
   </ol>
 
-  <p>A <span>heading content</span> element <span>represents</span> a <dfn data-x="concept-heading">heading</dfn>. 
-  The lower a <span data-x="concept-heading">heading</span>'s <span>heading level</span> is, the more important 
-  the <span data-x="concept-heading">heading</span> is.</p>
+  <p>A <span>heading content</span> element <span>represents</span> a <dfn
+  data-x="concept-heading">heading</dfn>. The lower a <span
+  data-x="concept-heading">heading</span>'s <span>heading level</span> is, the more important the
+  <span data-x="concept-heading">heading</span> is.</p>
 
   <p>The <dfn>document headings</dfn> are all <span data-x="concept-heading">headings</span> in a
   document, in <span>tree order</span>.</p>