[Plugin: list-catergory-posts] Grid issues, nth-child

Hi, I’m trying to put together a portfolio site using wordpress with the list-catergory-plugin. I am trying to set up a grid, but I cannot seem to select the last image in the row. I’ve tried using the selectors :first-child, :last-child, and :nth-child, but they don’t seem to work. I could be using them completely wrong, I only have a small knowledge of HTML and CSS and it’s by no means up to date. I believe I’m on the right track with the “:nth-child” selector, but I don’t know exactly how to make it select the ”

• ” I want it to.

I’ve found two threads addressing this issue, and neither of them were very helpful. I also looked at the FAQ of the plugin and their solution was to use tables, which seems a bit dated and doesn’t seem to translate to responsive design. If anyone has a solution to this, I would greatly appreciate your help.