Different images on desktop & mobile

Hi! I have an image on my client page  - https://www.blaineand.co/clients-carson
and have reformatted this to fit better on mobile - how can I I get the proper image to show up on each platform?
Thanks!

I'd like to keep the desktop version as is - and replace the image with the attached file on the mobile version 

With Image Block, you can add this code to Website Tools (under Not Linked) > Custom CSS to replace it with new image on mobile

@media screen and (max-width:640px) {
	#enter-image-block-id img {
		content: url(https://cdn.pixabay.com/photo/2023/12/24/15/03/bougainvillea-8467373_1280.jpg);
}
}

Replace Pixabay with mobile image url

Replace #enter...id with image block id. Use this free tool to find id: https://chrome.google.com/webstore/detail/squarespace-id-finder/igjamfnifnkmecjidfbdipieoaeghcff