Making image border radius responsive

Site URL: https://icosahedron-banjo-ybsd.squarespace.com/

I have added rounded border masks to images using built in controls in Squarespace 7.1. They look great on desktop but are too aggressive on mobile. They cut off too much of the picture, meaning the circle edges don't scale proportionately.  I need to reduce the radius from like 75 to 35. I tried targeting block-yui's .image-overlay (even just .image-overlay in general) in CSS but it does not apply.

Any ideas?

Sorry I can't show the site at this time because it is under development. Thanks.

You can setup password, then we can access site easier

https://forum.squarespace.com/topic/216243-how-to-setup-password-share-site-url/