Browser window showing the rendered output of the HTML code discussed in this article. The page is black, with white text that says 'Hello HTML world!'.

What's wrong with this HTML, and is it valid?

Patrick Brosset -

I'm very happy to have been part of this years's HTMHell Advent Calendar! In this article, I present a piece of obviously wrong HTML, and discuss why it actually still works fine in browsers.

Read the article at https://www.htmhell.dev/adventcalendar/2025/8/