> ## Documentation Index
> Fetch the complete documentation index at: https://ownpay.org/docs/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> OwnPay is licensed under AGPL-3.0 and is completely free - no licensing fees.
> Production docs URL: https://ownpay.org/docs - append .md to any page URL for clean markdown.
> OwnPay requires PHP 8.3+, MySQL/MariaDB, and Redis.
> MCP server available at https://ownpay.org/docs/mcp for programmatic documentation queries.
> Use root-relative links (e.g. /quickstart) for internal navigation - do NOT include /docs prefix.
> Plugin development: consult /developer/plugins/ pages for correct interfaces and manifests.
> Canonical locations: API auth = /api/authentication, webhook verification = /api/webhooks, rate limits = /resources/rate-limiting, transaction statuses = /fundamentals/payment-flow.
> The documentation uses the Diataxis framework: Tutorials (learning), How-to (tasks), Reference (lookup), Explanation (understanding).

# Checkout themes

> How to select, customize, and manage checkout page themes including built-in themes, theme plugins, and CSS overrides in OwnPay.

Themes control the layout and visual style of the checkout page your customers see. Each brand can use a different theme, so you can tailor the checkout experience per storefront.

## Select a theme

1. Go to **Appearance** → **Themes**.
2. Browse the list of installed themes.
3. Find the theme you want and click **Activate**.
4. The change takes effect immediately for all new checkout sessions.

## Built-in themes

OwnPay ships with a default theme that works for most use cases. It is responsive, supports light and dark modes, and renders correctly on all modern browsers.

<Note>
  Always keep the default theme installed as a fallback. If a custom theme has an error, you can switch back to the default instantly.
</Note>

## Custom themes via plugins

You can install additional themes through the plugin system. Custom themes are packaged as `.zip` files with a `manifest.json` and template files.

1. Click **+ Install Theme**.
2. Upload the theme `.zip` file.
3. The theme appears in your list.
4. Click **Activate** to use it.

For details on building your own theme, see [Theme development](/docs/developer/plugin-types/theme).

## Per-brand theme assignment

Themes are assigned at the brand level:

1. Go to **People** → **Brands** and edit a brand.
2. In the **Theme** section, select which theme this brand uses.
3. Click **Save**.

This lets you use a professional theme for one brand and a casual theme for another.

## CSS customization

If you need small visual tweaks without creating a full theme plugin, you can add custom CSS:

1. Go to **People** → **Brands** and edit the brand.
2. In the **Custom CSS** text area, enter your CSS rules.
3. These rules are injected into the checkout page after the theme stylesheet loads.

Use this for minor adjustments like changing font sizes, button border radius, or spacing. For major layout changes, create a proper theme plugin instead.

<Warning>
  Do not upload theme `.zip` files from untrusted sources. Theme files can contain PHP or JavaScript that runs on your server or in your customers' browsers.
</Warning>

## Related Pages

* [Branding](/docs/appearance/branding) - logos, colors, and favicons
* [Landing page](/docs/appearance/landing-page) - public page configuration
* [Theme development](/docs/developer/plugin-types/theme) - build custom theme plugins
* [Plugins overview](/docs/developer/plugins/overview) - how the plugin system works


## Related topics

- [AI Tools](/docs/developer/ai/overview.md)
- [Plugin Capabilities - Declare Features and Permissions](/docs/developer/plugins/capabilities.md)
- [OwnPay MCP Server - Connect AI Tools to Live Documentation](/docs/developer/ai/mcp.md)
- [Theme Plugin Development - Customize Checkout Appearance](/docs/developer/plugin-types/theme.md)
- [Customer Experience](/docs/checkout/customer-experience.md)