All of the images have only a constraint on the width, the aspect ratio is irrelevant. You can still do it with a grid, you just let the browser render the imag

All of the images have only a constraint on the width, the aspect ratio is irrelevant. You can still do it with a grid, you just let the browser render the images within as it would normally. Where it gets more complicated is getting them all to align horizontally at the bottom, which even this proposal doesn't do. Pinterest, of course, solved this by not having a "bottom."