How to Change Top Menu Bar Width

I am using the Make Child theme and am wondering how to make the top of the menu bar stretch the whole width of the screen? I’m referring to the top title, tag, and menu bar (such as About Me, Contact, etc).

I know there should be a simple way to do this considering the bottom footer stretches across the screen. Note I am not referring to stretching the middle content.

Please help! Thank you!