I wanted to try out the new GK Framework to see if it can replace Helix Ultimate for my site as a less weight heavy Framework.

But I am very confused about 2 things and the documentation doesn't really answer them that well.
For one the template width on large screens, I want to make it 100% with a cutoff of 1440px as max-width. But I set it in custom css file but the template does not read it. It still has the white space on the side of the content in the main body.

Also how does one add new positions to the template?
And if I add things to the main files as the documentation says, will those be saved in a template update or need to be re-done again with every new update?