Enforce Strict Columns on Archive Pages

Dear developers,

I am customizing my theme for an academic journal I’m running, and am hoping to see if I can get some advice/guidance on how to enforce strict columns on my archive pages. I want the text on the right-hand-side of the post image to remain in its column, rather than spill below the image after so many lines. In other words, I want one column of images and another column (probably not the correct word to be using, in terms of programming lingo) for the article information. Is there any way to do this?

The page I need help with: [log in to see the link]