Wider blog posts page/single post page

I’m trying to figure out how to make my blog posts page and the actual single blog posts wider like for example on my INFO page. I’ve tried many things but nothing seems to affect the blog feed/posts. I’m aware this will only affect people on desktops but I’d like the website to be structured the same way. Anyone can help me? I’m using Studiopress/Genesis.

The page I need help with: [log in to see the link]