Background images are not responsive by nature – it’s not a theme thing.
The focus and size of every background image are different as well so it’s impossible to set some sort of default desktop and mobile padding that works for everybody, unfortunately.
When we say the theme is completely responsive, it’s referring to all the elements that can be responsive – like mobile toggle shows up when the screen width is smaller and sidebar goes to the bottom of the page on mobile.
Let me know if this makes sense ๐