# Style invalidation

Working out which elements need styles recalculated after a change.

## What is **style invalidation**?

**Style invalidation** is the browser working out which elements need their styles recalculated after something changes, such as a class being added.

```javascript
document.body.classList.add("dark-mode");   // invalidates styles that depend on .dark-mode
```

Level: Master · [More CSS terms at this level](https://www.ask-codey.com/glossary/subjects/css/master)

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/style-invalidation