Webflow Content Lock

Design help General
1

https://preview.webflow.com/preview/donnas-spectacular-project-e0fcf9?utm_medium=preview_link&utm_source=dashboard&utm_content=donnas-spectacular-project-e0fcf9&preview=37b151df21de2bc1ef7c3f1002e4d6bd&workflow=preview

In the project I have a section which houses an article
And there is a div block positioned as fixed

How to disable scrolling of the article when the fixed div block is active? It is kind of a Content Lock for the article.
Like this :

image
image1673×891 139 KB

I can make the fixed div block appear/disappear using memberstack.

Here is my site Read-Only: LINK
(how to share your site Read-Only link)