Stop page scrolling behind modal window

Design help Custom code
1

I am trying to create a modal window on the page below. I’m having issues preventing the background from scrolling with the modal is open. Modal should open when the user clicks “Score breakdown”.

https://preview.webflow.com/preview/padel-fyi?utm_medium=preview_link&utm_source=designer&utm_content=padel-fyi&preview=f30beabf1fcb3dfdb988697f1c64b9b1&pageId=63ea59cff6d256d9506df03b&itemId=63ea59cff6d2562d7e6df1da&workflow=preview