That's not "HTML5-style"! HTML5 has nothing to do with this. HTML has always had optional closing tags when dealing with non-nesting elements. Purge the nonsens

That's not "HTML5-style"! HTML5 has nothing to do with this. HTML has always had optional closing tags when dealing with non-nesting elements. Purge the nonsense XML propaganda from your brain. Your example doesn't work though, as heading elements can contain paragraphs -- it's identical to "<h1>This is a header <p>This is some content.</p></h1>" A better example would be: <h1>This is a header</h1> <p>This is some content. <p>This is more content. <ul> <li>Red <li>Blue </ul>