Tokyo Full Screen Layout starts from left and stops in the middle of screen

In SharePoint 2013, why does the content inserted in a page with Tokyo full screen layout start from left of the screen and stop in the middle? How can I make the content go all the way to the right hand side of the screen?

Looking for a best practice solution. I've tried doing things like modifying tokyo.css, tokyo-alternate.css and even specifying my own custom css. I can change different styles except stretching the content across the page - which ideally I should not be required to do since Tokyo is a full screen page layout.