# Custom Code

Custom HTML, CSS, and JavaScript can be added to extend your documentation.

## How It Works

Custom code is injected into the `<head>` tag of your documentation site and applies to all published pages. This allows you to add external scripts, stylesheets, and custom JavaScript functions to enhance your documentation.

## Common Uses

### Analytics

- Google Analytics or Plausible for usage tracking
- Event tracking and user behavior analysis
- Custom metrics and dimensions

### CSS Customization

- Custom fonts and colors
- Layout modifications
- Mobile responsiveness adjustments
- Print styles

### External Tools

- Chat widgets
- Feedback forms
- Search enhancements
- Authentication systems

## Best Practices

### Performance

Your custom code directly impacts site performance. Load external resources asynchronously when possible and minimize HTTP requests. Use compression and minification for your code to reduce load times.

### Security

Keep security in mind when adding custom code. Use HTTPS for external resources and avoid storing sensitive data in client-side code. Regularly update any third-party dependencies and always validate dynamic content.

### Implementation

Custom code changes apply directly to your live site without a preview environment. Before adding any code, check for syntax errors and test thoroughly. Since invalid code can break your documentation, always back up your customizations and verify browser compatibility.