How to extend the background further?

Question

css

Good day. The background size is more than enough. If I delete all nested blocks, then the background is displayed normally, but it does not lay down normally when I add nested blocks. The background is not defined anywhere except in the main div.

Answer 1

background-color not set?)
as I understand it, our bottom band is uniform in color.
Or misunderstood the point.

Answer 2

background-image: url('урл_к_вашей_картинке');
background-size: cover;