Hi @MrInk, at the moment, if you open a modal and need to set the body to overflow hidden, so that the content on the page does not scroll, a little custom code is needed. You can trigger the custom code by ID applied to your buttons.
Take a peek here: How to disable scrolling on content *under* lightbox popup? - #2 by cyberdave
Here is an example site using a little custom code in the Before Body section of the page settings: https://webflow.com/website/Disable-Body-Scroll-Example
I hope this helps