I've been trying to understand how WordPress picks images to use depending on the size of the user screen, but I've been unable to figure it out.
Is it just by checking if the request is coming from a mobile or desktop device? I have a photo site that would like to cater to 4k screens, so I have a featured images of 2400px * 1120px.
I know a version that has a width of 1536px is generated. On my mac, my the featured image is displayed as 1425px * 665px (1425px is the full width of my browser window). Why doesn't WordPress use the 1536px width image that was automatically generated instead of the 2400px width original?