HTML Guide
A main element cannot be nested within another main element.
The main element represents the primary content of a document or application, and there must be only one per page, not placed inside another main. The main element must not be used as a descendant of another main element. This is important for accessibility, semantic correctness, and helps screen readers correctly identify the main content region.
Invalid example (nested main):
<main>
<h1>Welcome</h1>
<main>
<p>This nested main element is invalid.</p>
</main>
</main>
Valid example (single main only):
<main>
<h1>Welcome</h1>
<section>
<p>This section is valid and can be placed inside main.</p>
</section>
</main>
If you need to divide the main content, use sectioning elements like section, article, or div inside a single main element, but never nest main inside main.
Learn more:
Related W3C validator issues
There can only be one visible <main> element in a document. If more are needed (for example for switching between them with JavaScript), only one can be visible, the others should be hidden toggling the hidden attribute.
Example of 2 main elements, where only one is visible:
<main>
<h1>Active main element</h1>
<!-- content -->
</main>
<main hidden>
<h1>Hidden main element</h1>
<!-- content -->
</main>A main element cannot be placed inside an article element according to HTML5 content model rules.
The main element is intended to identify the dominant content of the <body> that is directly related to, or expands upon, the central topic of a document. It is meant to be unique, appearing only once per document, and must not be a descendant of elements like article, aside, header, footer, or nav. Conversely, the article element represents a self-contained composition that could independently be reused or distributed, such as a blog post or news story.
To resolve the error, move the main element so that it is a direct child of the body, and place any article elements inside the main or at the same level, not the other way around.
Incorrect:
<article>
<main>
<h1>Article Title</h1>
<p>This is the article content.</p>
</main>
</article>Correct:
<main>
<article>
<h1>Article Title</h1>
<p>This is the article content.</p>
</article>
</main>Minimal valid HTML document:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Article in Main Example</title>
</head>
<body>
<main>
<article>
<h1>Article Title</h1>
<p>This is the article content.</p>
</article>
</main>
</body>
</html>Use only one main element per page and ensure it is not nested inside sectioning elements such as article.
The main element represents the dominant contents of the document, so it should not be contained within another section.
A document must not have more than one main element that does not have the hidden attribute specified.
A hierarchically correct main element is one whose ancestor elements are limited to html, body, div, form without an accessible name, and autonomous custom elements. Each main element must be a hierarchically correct main element.
The main landmark role is used to indicate the primary content of a document. It can be added to an element by using role="main", but instead it’s preferable to just use the <main> element. In that case, it’s unnecessary to make the main role explicit. Examples:
<div role="main">
<!-- this is a valid way to define a main role -->
</div>
<main>
<!-- but this is shorter and uses correct semantic HTML -->
</main>