space between the latest posts in content sidebar

Dear, I set the latest posts on in content sidebar, and then gave small modifications through CSS, such as the size of pictures, and size of fonts. Nevertheless, I could never modify the space between each latest post. For exampkle, in my site, it refers to the space between the entry-summary and the entry-title. As you can see, there is a huge space (padding? margin?) in between. I simply want to reduce it through CSS. I kept my eyes peeled for how to change it on a trial-and-error basis. But, in the end I threw the game. My site URL is http://kenta-kiyomiya.com/ I'm terribly sorry to bother you, but it's very important for me. Thank you