I would somebody help me to make some change to the default style of k2.
To be more specific I would like the style of the image I have attached here.

https://www.dropbox.com/s/xvwa45duxjuexdm/k2-style.jpg?dl=0

Actually, I would like to have a background and in the end of the article to be a line in order to can separate one article from another.

Best Regards.

You can use a new <div> element at the end of the category_item.php file with a css background.