How to avoid scrolling in an entire page?

[Alexis]

Someone else seems to already have solved your exact case

Disable scroll on body when modal is launched

Hey everyone … when a modal is launched we’d like to disable the scroll on main body. For example, if a user scrolls and there is nothing to scroll on the modal itself, the position on main page shifts. On mobile this causes problems with the nav bar appearing/disappearing. Anyone have ideas about how to disable background scroll when modal is launched? Thanks!