# End tag “u” violates nesting rules.
> Canonical HTML version: https://rocketvalidator.com/html-validation/end-tag-u-violates-nesting-rules
> Attribution: Rocket Validator (https://rocketvalidator.com)
> License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
The closing `` tag appears while an element opened inside the `` is still open, so the two elements overlap instead of nesting.
HTML elements form a tree, and the element opened last has to be closed first. In `Shipping details`, the `` starts inside the ``, but `` comes before ``. The parser can't end the `` without also ending the ``, so it repairs the markup with the [adoption agency algorithm](https://html.spec.whatwg.org/multipage/parsing.html). When text sits between the two end tags, as in `Shipping details`, the browser opens a second `` for that text. The DOM then has two `` elements where your source has one, and a CSS rule like `u b` styles only the first.
When nothing sits between the end tags, the leftover `` has nothing to close, and the validator follows this error with a second one saying no `b` element is in scope. Fixing the order clears both.
Close the elements in the reverse order you opened them. If the `` opened inside the ``, the end tags go ``.
The `` element is for text with a non-textual annotation, such as a misspelled word. If the underline is only decoration, use CSS `text-decoration: underline` instead, and keep in mind that readers often take underlined text for a link.
## Invalid example
```html
Shipping details
```
## Valid example
```html
Shipping details
```