> For the complete documentation index, see [llms.txt](https://docs.csspro.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.csspro.com/quick-start/installing/on-firefox.md).

# On Firefox

### How to install CSS Pro on Firefox:

To follow these steps, **you need to have purchased a CSS Pro license key**. If you don't have one yet, [**get one here**](https://gum.co/csspro?wanted=true).

{% embed url="<https://www.youtube.com/watch?v=wPaiE5baXxQ>" %}
Video tutorial
{% endembed %}

**Step 1.** **Download the Firefox extension from the link you were redirected** to after buying it or your Gumroad receipt (in your email) or [library](https://gumroad.com/library). If you can't find it, please download the extension via the [My License](https://csspro.com/my-license) page.

**Step 2.** **Drag and drop** the **"Firefox.xpi"** file **into your Firefox** browser window, and click on the button "Add" to install the add-on.

![Click on "Add"](/files/rsvWIaXHvHdw6FDrkGuq)

Now that you have the extension installed, it's time to activate it with a license key, which you've got in your receipt, but can also be retrieved [here](https://cssscanpro.com/my-license) if you forgot/lost it.

**Step 3. You're going to be redirected to a webpage. If that doesn't happen, open any website on a new tab**, for example, Google or your own website.

**Step 4.** **Click on CSS Pro's icon** on your **toolbar** to open the extension:

![](/files/PwYsMijCKOA8qA4I8icF)

A modal (popup) will appear asking for the license.

**Step 5. Input your license key** and validate it by clicking on **"Activate"**:

![](/files/fqtUufqTMf2whS4GQSKq)

🎉 **Done!** Your license is now activated, and you can use CSS Pro anywhere else.‌

The extension will not ask for your license again (unless deactivated or disabled).‌

To manage your license activations in the future, use [the My License page](https://cssscanpro.com/my-license).


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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, and the optional `goal` query parameter:

```
GET https://docs.csspro.com/quick-start/installing/on-firefox.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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.