Which I also do not want, I only want the images to be either in a 1 x 3 grid or a 3 x 1 grid, no other combinations. And when they are in those configurations, they scale to take up the width of the page.
I’m trying it out right now but the fixed width on all three boxes means that the boxes won’t stretch to fill out the page. Have you found a way to do it without the fixed width?
Also, putting the above aside for a second, I am trying to implement what you said but not getting it to work. When you say, make the rightmost box fixed margin on the right, do you mean the rightmost box or the rightmost group? I have tried both and they both still end up with 2 at the top and one underneath.