Help with SKT Full Width Theme?

Hey there, I’m having a few problems so help with this would be appreciated.

Firstly, my posts only take up half of the page.
https://ipadcaseatkeyboard.com/test-post/
Is there a way to fix this?

Secondly, there’s a weird brown border around my post thumbnails on each category page.

https://ipadcaseatkeyboard.com/category/ipad-cover-art/

If i can’t fix this I’d like to use a different theme, any suggestions of ones that look like this?

https://www.waycoolgadgets.com/category/clever/

Thanks for the help!