Add a larger margin on alle content but background image

[Snitt]

I am trying to keep the background image full width while adding a larger margin to all other content.

This is my css now:

body {
max-width:90%;
margin:auto;
}


I have tried alot of different solutions and can mention some here
- background-image:100% !important;
- min-width to element with backgroundimage.
- body:not(.elementwithbacgroundimage)

All help is appreciated.