Ok, so I touched it a little.
If anyone hates it too much, or it's broken somehow, let me know how to fix it, since I have no idea about CSS.
I think the code snippets look a lot better now, and specially, thanks to Georg's tip, they don't screw the layout anymore.
One weird thing, though (not really related).
Apparently, long ago, I knew how to put the source of the item on a post (see here, the Source KDE Dot News part).
Either the option is gone, or I forgot how to do it. Even if I edit that old post, I can't see where it is.