> ## Documentation Index > Fetch the complete documentation index at: https://docs.authsignal.com/llms.txt > Use this file to discover all available pages before exploring further. # Custom branding > Customize the look and feel of the pre-built UI to match your app's brand. For a more seamless user experience you can heavily customize the pre-built UI branding by providing your own theme. Visit the [branding tab in the Authsignal Portal](https://portal.authsignal.com/organisations/tenants/customizations) to get started. If you require a more bespoke branding experience then try out our [UI customization tool](https://portal.authsignal.com/organisations/tenants/customizations/advanced). This tool allows you to change a wide range of design tokens (colors, borders, alignment, text) to tweak the look and feel of the entire pre-built UI.

## Custom templates To override the pre-built UI's layout you can provide a custom template. Custom templates, at a bare minimum, must contain the following structure. ```html theme={null} ``` The `authsignal-head` and `authsignal-widget` tags are required for the pre-built UI to function correctly. To update your tenant's custom template, you can send the following payload to the [Update Theme endpoint](/api-reference/management-api/update-theme). ```json theme={null} { "template": "" } ``` The `template` string must have escaped special characters. ## Adding custom HTML/CSS Using a custom template allows you to add your own HTML/CSS. For example, if you wanted to show an image next to the pre-built UI you could use the following template: ```html theme={null}

``` Which would result in:

## Adding custom JavaScript To add custom JavaScript to your custom template you can use the following structure: ```html theme={null} ```