> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt.

## WebSocket Support in API Playground

api-reference

Added real-time WebSocket testing capabilities to the API playground, enabling developers to test streaming and real-time endpoints directly in the documentation. WebSocket connections can now be established, tested, and debugged without leaving the docs.

## Enhanced Code Highlighting

customization, performance, writing-content

Implemented a new code highlighting system using Shiki for improved syntax highlighting accuracy and performance. The system now supports more languages and provides better dark mode compatibility.

## Feedback System

customization

Introduced a new feedback collection system using Radix UI components for improved accessibility. Users can now provide structured feedback about documentation quality and usefulness directly within the interface.

## Layout Configuration System

customization

Implemented a flexible layout configuration system that allows for custom header, footer, and sidebar arrangements. Documentation can now be customized to match your brand and preferences.

```yaml
layout: 
  page-width: full
  tabs-placement: header
  searchbar-placement: header
```

## Custom Styling Support

customization, docs.yml

Added support for custom CSS and scripts, enabling deep customization of documentation appearance and behavior. Organizations can now apply their branding consistently across their documentation.

**`docs.yml`**

```yaml docs.yml
  css: ./assets/styles.css
```

**`styles.css`**

```css styles.css
/* Custom styles */
.custom-class {
  background-color: #f0f0f0;
}
```

Read the docs