Download Extension from Chrome Web Store:
 https://chrome.google.com/webstore/detail/squarespace-ninja-kit-ext/klkcninekpnpemndealaeebjajmkabcf

Step 1 - Add HTML code

In the Home Menu, click Settings, click Developer Tools, and then click Code Injection and add the below code for the Header.

• HEADER

<!-- Upgrade your website to the next level - NinjaKit --> <link rel="stylesheet" href="https://ninjakit-assets.ixstudio.net/assets/admin/css/ninja-sqs.css" id="ninjakit-css"> <script src="https://ninjakit-assets.ixstudio.net/assets/admin/js/ninja-sqs.js" id="ninjakit-js" defer></script> <script src="https://ninjakit-assets.ixstudio.net/assets/admin/js/platform.js" id="ninjakit-pro-js" defer></script> <!-- NinjaKit -->

Step 2 - Save!

After adding your code, click Save.

Step 3 - Check this video to learn how it works!

That's all! Enjoy it 🙂