# Stacking context

A group whose layers stack together; z-index only compares within it.

## What is a **stacking context**?

A **stacking context** is a group whose layers stack together. `z-index` only compares elements inside the same group, which is why a huge `z-index` sometimes doesn't help.

```css
.card { position: relative; z-index: 1; }   /* a new stacking context */
.card .menu { z-index: 9999; }   /* can't rise above elements outside .card */
```

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/stacking-context