Looks good! I had a quick second to install it and give it a try and yes, all the images are displaying.
Now I have to get it to work on the third party style properly. Works perfectly on the default XF style, but third party, I have the content width narrower and the bottom margins are bleeding into the tops of the images in the following row, along with the date wrapping onto new lines.
I don't really want to let the page stretch out wider but on the other hand, that might be best. Or I may just do away with the sidebar, as that is forcing things smaller than they need to be.
So I just need a little tweaking here and there, and I think we'll be rockin' this 4-across for Classifieds.
What I've been doing is using a template modification to insert this code into extra.less, so it affects all styles. Then I can tweak an individual style separately if needed. It's made a world of difference, as I put all of what I call my "common" extra.less edits into template modifications, then wrap them up into an add-on that I can easily transport to the live forum when I do the upgrade.
Having data-page-key available as an attribute such as [data-page-key="page-1"] would be useful for styling purposes. That would make it easy to, for example, style the first page of an article forum separately from the subsequent pages.
From what I understand, then, I can use code like [data-container-key="node-87"] in template modifications for .less documents to affect only the specified node(s)? If so, that would actually solve a couple other issues for me.