The system width can be used to change the width of the system.
What we mean by system width is the width of the bxp area in the browser.
In the image below the red area is the system width and everything outside is the browser width.
So when the width is change the box in red will be resized, nothing else.
[[File:Interface_Background_Width.jpg]]
This can be useful if the the screen size is rather small that the system will appear on.