# Underline Collapsible

> A collapsible section whose trigger reveals its content while an animated underline sweeps, centers, grows, doubles, or dashes in beneath the label, with five visual variants and four sizes.

- Author: [ai 2](https://21st.dev/@ai2)
- Library: @ai2
- License: MIT
- Tags: Accordion, Animation, Framer Motion, Collapsible, Underline
- npm dependencies: motion, lucide-react
- Live preview: https://21st.dev/@ai2/components/collapsible-underline

## Install

```bash
npx shadcn@latest add "https://21st.dev/r/ai2/collapsible-underline?api_key=$API_KEY_21ST"
```

Requires a 21st API key (generate one at https://21st.dev/mcp) passed as `API_KEY_21ST`. Free accounts get a limited number of installs per day; unlimited on a paid plan — see https://21st.dev/pricing.

Full component directory: https://21st.dev/llms.txt · More like this: https://21st.dev/community/components/s/accordion.md