如何将两个元素并排放置?

I am quite new to the world of CSS, and I've been trying to figure out how to position the .main and .comment side by side in the example at the end, with one caveat. I don't want to squeeze both into the same #container, I would like the comment to sort of "pop" out of the bounding box, and be aligned with the .main but outside of #container. The reason I want to do this is that the comment would initially be hidden and after the user clicks on something, the comment would sort of pop open. I am quite new to the world of CSS, and I've be