# Introduction

We can use custom in situations when we want to add extra interactivity to our responsive creative. Use the Radical API to access elements added from the editor, update their behavior, and add custom functionalities to your ad.

You can use all available JavaScript functions to manipulate element position and size. This is usually done by changing the DOM element  CSS ‘style’ property. All elements in creative are positioned absolutely with inline styles set by our rendering script. 

On the left side, you can add your custom CSS. When targeting individual elements, make sure that you use a CSS selector that is specific enough.<br>

{% content-ref url="/pages/JMIYX1pJueQB5bnRDPRJ" %}
[Custom JS](/developers/custom-js.md)
{% endcontent-ref %}

{% content-ref url="/pages/jVQPQRQQXZExkZ8wbKIn" %}
[Radical API](/developers/radical-api.md)
{% endcontent-ref %}

### Getting started <a href="#getting-started" id="getting-started"></a>

You can use the built-in code editor you can find inside the editor page, or you can use `npx` to create a local code repository.

To get started, create a new application following the instructions, then read about how to access components and use Radical API to its full capabilities.


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.responsiveads.com/developers/introduction.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.