HTML Guide

Stray start tag “style”.

A <style> start tag has been found in an unexpected place in the document structure. Check that the <style> section appears within the <head> section.

Although in general it’s better to put your styles in external stylesheets and apply them using <link> elements, CSS styles can also be included inside a document using the <style> tag. In this case, it should be placed within the <head> section, like in this example:

<!DOCTYPE html>
<html>
  <head>
    <title>Test</title>
    <style>
      p {
        color: #26b72b;
      }
    </style>
  </head>
  <body>
    <p>This text will be green.</p>
  </body>
</html>

Learn more:

MDN: style element

Related W3C validator issues

Stray start tag “head”.

A <head> start tag has been found in an unexpected place in the document structure. Check that the <head> section appears before the <body> section, and that is not duplicated.

The <head> section of an HTML document is the container of metadata about the document, and must appear before the <body> section. A common cause of this issue is duplicated <head> sections.

Here is an example of a minimal HTML document structure:

<!DOCTYPE html>
<html>
  <head>
    <title>Test</title>
  </head>
  <body>
    <p></p>
  </body>
</html>

Stray start tag “html”.

Stray start tag “noscript”.

The “Stray start tag noscript“ error in the W3C HTML Validator indicates that the <noscript> tag has been used incorrectly or is placed in an invalid location within your HTML document.

The <noscript> tag is used to define alternative content for users who have disabled JavaScript in their browsers or for browsers that do not support JavaScript.

Common Causes:

Position of <noscript>: The <noscript> tag should be placed correctly within sections where it is allowed.
Nested Improperly: The <noscript> tag should not be placed inside other tags where it is not valid.

Correct Usage:

Within <head>:

 <head>
     <title>Example Page</title>
     <script>
         // Some JavaScript code
     </script>
     <noscript>
         <style>
             /* Alternative styling if JavaScript is disabled */
         </style>
     </noscript>
 </head>

Within <body>:

 <body>
     <h1>Welcome to the Example Page</h1>
     <script>
         // Some JavaScript code
     </script>
     <noscript>
         <p>JavaScript is disabled in your browser. Please enable JavaScript for the full experience.</p>
     </noscript>
 </body>

Fixing the Issue:

Inside Existing Tags: Ensure the <noscript> tag is not placed inside other tags where it cannot be parsed correctly.

 <!-- Incorrect -->
 <div>
     <noscript>
         <p>JavaScript is disabled in your browser.</p>
     </noscript>
 </div>
 
 <!-- Correct -->
 <noscript>
     <div>
         <p>JavaScript is disabled in your browser.</p>
     </div>
 </noscript>

Placement in Body or Head: Verify that the <noscript> tag is placed inside the <body> or <head> based on what content it’s providing a fallback for.

 <!-- Incorrect (inside an illegal tag) -->
 <div>
     Some content
     <noscript><p>JavaScript is disabled in your browser.</p></noscript>
 </div>

 <!-- Correct -->
 <div>Some content</div>
 <noscript><p>JavaScript is disabled in your browser.</p></noscript>

Summary:

Place <noscript> only within accepted sections (<head> or <body>).
Avoid nesting <noscript> inside other tags improperly.

Stray start tag “script”.

A <script> start tag has been found in an unexpected place in the document structure. Check that the <script> section appears within the <head> or <body> sections.

Here’s an example of a script inserted in the head of the document:

<!DOCTYPE html>
<html>
  <head>
    <title>Test</title>
    <script>
      console.log("Hello from the head");
    </script>
  </head>
  <body>
    <p></p>
  </body>
</html>

Stray start tag “section”.

The “Stray start tag “section”” error in the W3C HTML Validator typically occurs when a <section> tag appears in an unexpected location within your HTML document structure. This can happen if the <section> tag is not positioned correctly within the HTML5 content model.

Here’s a focused guide to fix this issue:

1. Check the Parent Element

Make sure the <section> tag is placed within elements where it is allowed. According to the HTML5 specification:

A <section> element should be placed within the <body> tag.
It should not be a direct child of an inline element or an element that does not support flow content.

2. Correct Nesting Within Elements

Ensure your HTML structure follows a logical hierarchy and that the <section> element is not incorrectly nested. This example shows a correct usage of the <section> tag:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Correct Usage of Section</title>
</head>
<body>
    <header>
        <h1>Page Title</h1>
    </header>
    
    <nav>
        <!-- Navigation links -->
    </nav>
    
    <main>
        <section>
            <h2>Section Title</h2>
            <p>Content for the first section.</p>
        </section>
        
        <section>
            <h2>Another Section Title</h2>
            <p>Content for the second section.</p>
        </section>
    </main>
    
    <footer>
        <p>Footer content</p>
    </footer>
</body>
</html>

3. Check for Mistaken Hierarchy

Verify whether the <section> tag is mistakenly placed inside elements that do not support it, such as directly inside a <p> tag or other inline elements. Correct any incorrect usage. For example this is incorrect usage because the <section> tag is placed after the closing <body> tag:

Incorrect:

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Sample page</title>
</head>
<body>
  <h1>Main title</h1>
  <p>Some content</p>
</body>
</html>

<section>
  <h2>Incorrect Section</h2>
  <p>This section should not be after the closing body tag.</p>
</section>

Correct:

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Sample page</title>
</head>
<body>
  <h1>Main title</h1>
  <p>Some content</p>

  <section>
    <h2>Correct Section</h2>
    <p>This section is fine.</p>
  </section>
</body>
</html>

Summary

Ensure your <section> tags are used within the <body> tag and other allowed elements.
Maintain a logical hierarchy in your HTML document.
Avoid placing <section> tags inside inline elements like <p>.

Following these steps should resolve the “Stray start tag “section”” error in your HTML document. Validate your HTML again after making these corrections to ensure the issue is resolved.

End tag X did not match the name of the current open element Y.

Start tag “a” seen but an element of the same type was already open.

An <a> tag can’t include other <a> tags inside. Most probable cause is an unclosed <a> tag, like in this example:

<a href="one.html">Page 1
<a href="two.html">Page 2</a>

Start tag “button” seen but an element of the same type was already open.

Start tag seen without seeing a doctype first. Expected “<!DOCTYPE html>”.

HTML documents are expected to start with a first line containing the Document Type Declaration, that defines the HTML version used. Since HTML5, it’s just <!DOCTYPE html>, which must appear before the start <html> tag.

Here’s an example of a minimal HTML5 document:

<!DOCTYPE html>
<html>
  <head>
    <title>Test</title>
  </head>
  <body>
    <p></p>
  </body>
</html>

Stray doctype.

All HTML documents must start with a <!DOCTYPE> (Document Type Declaration), that informs browsers about the type and version of HTML used to build the document. In HTML5, this is simply <!DOCTYPE html> and must appear at the start of the document.

Here is an example of a minimal HTML document, including the Document Type Declaration at its start:

<!DOCTYPE html>
<html>
  <head>
    <title>Test</title>
  </head>
  <body>
    <p></p>
  </body>
</html>