Good morning….Not sure of the area you are referring to but will assume you mean the content and breadcrumbs area. The CSS that does this is around line 224 of the style.css file which looks like this:
The padding is the part that you want to override with your own custom CSS.
As for the space where the edit link is, hard to say because that is located in different positions, but the above method might help. Also, if you do not use the “edit” link (which only shows when you are logged in), you can disable that by going to Appearance >> Customize >> Basic Settings >> Hide Edit Link