I am making my first steps coding. I made some courses on Internet and now I am building a wordpress theme to continue learning from the practice.
I have a child-theme from the twenty sixteen theme. I found that in the customize section in the wordpress admin I can change the background of the site and also something that is the background of that background. It's something a bit strange for me.
I am looking everywhere in the css code of the theme to remove that but I can't find it. Is it possible to only have that white section? and not that yellow block?
UPDATE:
I find that it's called body .custom-background but what I don't understand is what is that? what is the difference between that an my page that I can set to white? Is not possible to make my page in the window inner height? That yellow thing is like something that makes the limit of my page.

