# Customise Themes

BlueBase supports different types of theme customisation requirements so that a developer can do a single usage customisation or globally override a theme.

## Override all themes

There may be use cases where you may need to keep specific values same, n matter which theme is selected, i.e. primary colours, etc.

To do this, use the `theme.overrides` config. This change is global, and overrides all installed themes.

{% code title="bluebase.ts" %}

```typescript
const bootOptions = {

	configs: {
		'theme.overrides': {
			components: {
				// component styles
			}
		}
	},
};

export default bootOptions;
```

{% endcode %}

## Specific variation, global usage

Extend a theme

```typescript
import { createTheme } from '@bluebase/core';

// ... TODO: current api may change
```

## Specific variation, one time usage

Using the `ThemeProvider` overrides prop. This change is only for this tree.

* Nesting themes
* Overriding themes

### Nesting Themes

It is possible to nest multiple themes in a single project. To theme a specific portion of your app, use the `ThemeProvider` component.

```jsx
<BB.Components.View>
	<BB.Components.Text>Default light theme here</BB.Components.Text>
	<ThemeProvider theme="bluebase-dark">
		<BB.Components.View style={{ backgroundColor: theme.palette.background.default }}>
			<BB.Components.Text>Dark theme here</BB.Components.Text>
		</BB.Components.View>
	</ThemeProvider>
<BB.Components.View>
```

 In the example above, we pass the `theme` prop to the `ThemeProvider` component. This prop takes the key of the theme to use for children components. If this prop is not set, the globally selected theme is used.

### Overriding Themes

The `ThemeProvider` component can also be used to override a theme for a one time usage.

```jsx
<ThemeProvider theme="bluebase-dark" overrides={{ palette: { background: { default: 'red' } } }} >
	{/* All components here will now have a red background color */}
</ThemeProvider>
```


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