# Overview

Source: https://docs.interop.io/desktop/capabilities/windows/themes/overview/index.html

## Overview

**io.Connect Desktop** has two built-in themes - dark and light. You can control the themes programmatically by using the Themes API.

It's possible to customize the styles of the **io.Connect Desktop** system web apps ([Workspaces App](https://docs.interop.io/desktop/capabilities/windows/workspaces/overview/index.md#workspaces_concepts-workspaces_app), [web groups](https://docs.interop.io/desktop/capabilities/windows/window-management/overview/index.md#window_groups-web_groups), [Launchpad](https://docs.interop.io/desktop/capabilities/launcher/index.md#launchpad), [modal windows](https://docs.interop.io/desktop/capabilities/windows/modals/overview/index.md), and more) via [CSS variables](https://docs.interop.io/desktop/developers/platform-styles/index.md).

If you are using [classic groups](https://docs.interop.io/desktop/capabilities/windows/window-management/overview/index.md#window_groups-classic_groups), you can customize the platform themes via the `themes.json` [themes configuration](https://docs.interop.io/desktop/developers/configuration/themes/index.md) file of **io.Connect Desktop**.

> ℹ️ *For details on how to customize the **io.Connect Desktop** themes via CSS, see the [Developers > Platform Styles](https://docs.interop.io/desktop/developers/platform-styles/index.md) section.*

> ℹ️ *For details on configuring the **io.Connect Desktop** themes via the `themes.json` file when using classic groups, see the [Developers > Configuration > Themes](https://docs.interop.io/desktop/developers/configuration/themes/index.md) section.*

### Default Theme

The default theme for **io.Connect Desktop** can be automatically synchronized with the default app mode in your OS via the `system.json` [system configuration](https://docs.interop.io/desktop/developers/configuration/system/index.md) file. To specify your preference, use the `"syncWithDefaultOSAppMode"` property of the `"themes"` top-level key:

```json
{
    "themes": {
        "syncWithDefaultOSAppMode": true
    }
}
```

> ℹ️ *For more details on the available configuration settings for the io.Connect themes, see the [Developers > Configuration > System > Themes](https://docs.interop.io/desktop/developers/configuration/system/index.md#themes) section.*