I have just written a tutorial on how you can reduce space between Blogger gadgets. I guess I might as well write a tutorial on this one, since you have to address the elements in this one in a slightly different manner. How different one might ask. Most gadgets are unique, so normally they have their own IDs. However, it is difficult to find an ID for your post structures since post structures are identified using classes. Please refer to this post on a brief note about IDs and Classes.