Blogum: Increase gap between content and right side bar lines going across pg

I’m trying to increase the gap between the content and the right side bar – How do I do this?

Also, I’ve noticed that the lines that separate the boxes on the right side bar make their way across the whole page. How do I stop this from happening?

my site is at https://www.argutori.com

Let me know if I need to post some of the CSS code