Hi Dan,
Thank you that does solve the cropping, I was looking to use code that would let me replace the image when viewed on mobile, so I could use an image like below. I previously did this for banner images and this is the code I used:
media only screen and (max-width: 640px){
#page .page-section:nth-child(1)
.section-background img {
opacity:0
}
#page .page-section:nth-child(1)
.section-background {
background-image: url(https://static1.squarespace.com/static/607fd834cc2b3d1c6038d54a/t/608175fa695dc47c58640bb7/1619097084730/studysuite+mobile+banner+ai.png);
background-size: cover;
background-position: center;
background-repeat: no-repeat;
}
}