Website Scroll clash with Iframe / <embed

Hey all,

Currently running into an issue of having multiple scrolls throughout a website: https://prodyonda.com/store

After clicking on a shirt design, you'll see the issue of clashing scroll bars, one within the Iframe and one within the page itself.

Using an IFrame / <embed to integrate a clothing store website into my pre-existing Squarespace website and encountering issues with clashing scrolls, (the main web page & the Iframe), its not a major issue although does get clunky from a consumer experience. 

Goal is to be able to have '1' main scroll for the pages within the website and to be able to view all content contained within the Iframe / <embed just like other clothing website, (Gucci, Culture Kings etc. for example)

Thanks very much,

YONDA.