Hi!
I have created a new page which has TT post category element with the latest post of one category. I have attached you a screenshot in order to see that there is a bottom border at the end of each post that continues at the sidebar area. 
https://prnt.sc/mbfxmd
It seems like the wrapper of the posts covers the sidebar area. If you want to see the page live is at https://sindimotes.com/deltia-tipou/
I will also want to ask if it is possible to hide the author of the posts.
Thanks