# App shell
Source: https://signy.dev/examples/app-shell/
Three contexts, provided once, used anywhere below.
The root provides a session, a theme and a notifier. The user menu, the theme switch and any page inject what they need, with no props passed through the layers between.
## Preview
[Open the page on its own](https://signy.dev/examples/app-shell/demo/index.html.md)
## Code
Save it as an `.html` file and open it in a browser. It loads Signy and Iris CSS from the CDN, so there is nothing to install or build.
**Show the full page**
```html
App shell - Signy example
```
## What it uses
- [createContext() and createRequiredContext()](https://signy.dev/documentation/1/components/context/index.html.md)
- [Signals](https://signy.dev/documentation/1/reactivity/signals/index.html.md) as context values
- [For](https://signy.dev/documentation/1/templates/for-and-index/index.html.md) for the toast stack