If you don't find the features you're looking for, or you would rather create your own theme, you may customize VitePress to fit your requirements. In the following sections, we'll go through each way of customizing the VitePress theme.
// app is the Vue 3 app instance from `createApp()`.
// router is VitePress' custom router. `siteData` is
// a `ref` of current site-level metadata.
}
}
```
...where the `Layout` component could look like this:
```vue
<!-- .vitepress/theme/Layout.vue -->
<template>
<h1>Custom Layout!</h1>
<!-- this is where markdown content will be rendered -->
<Content/>
</template>
```
The default export is the only contract for a custom theme. Inside your custom theme, it works just like a normal Vite + Vue 3 application. Do note the theme also needs to be [SSR-compatible](./using-vue#browser-api-access-restrictions).
To distribute a theme, simply export the object in your package entry. To consume an external theme, import and re-export it from the custom theme entry:
```js
// .vitepress/theme/index.js
import Theme from 'awesome-vitepress-theme'
export default Theme
```
## Extending the Default Theme
If you want to extend and customize the default theme, you can import it from `vitepress/theme` and augment it in a custom theme entry. Here are some examples of common customizations:
### Registering Global Components
```js
// .vitepress/theme/index.js
import DefaultTheme from 'vitepress/theme'
export default {
...DefaultTheme,
enhanceApp({ app }) {
// register global components
app.component('MyGlobalComponent', /* ... */)
}
}
```
Since we are using Vite, you can also leverage Vite's [glob import feature](https://vitejs.dev/guide/features.html#glob-import) to auto register a directory of components.
### Customizing CSS
The default theme CSS is customizable by overriding root level CSS variables:
```js
// .vitepress/theme/index.js
import DefaultTheme from 'vitepress/theme'
import './custom.css'
export default DefaultTheme
```
```css
/* .vitepress/theme/custom.css */
:root {
--vp-c-brand: #646cff;
--vp-c-brand-light: #747bff;
}
```
See [default theme CSS variables](https://github.com/vuejs/vitepress/blob/main/src/client/theme-default/styles/vars.css) that can be overridden.
The default theme's `<Layout/>` component has a few slots that can be used to inject content at certain locations of the page. Here's an example of injecting a component into the before outline:
