Placekitten.com is a free online placeholder generator. Just make your link by specifying width and height desired (in pixels,) like so:
These images, as they are now, are not responsive, (excepth the one on the bottom of the page is, because it's in a different format.) These others remain their original size. I'll need to study Bulma more in order to actually do a layout like this right. I am also not fond of the section border (faint grey line.) Bulma looks quite capable, but I'm not quite there yet.