Custom Backgrounds is a theme feature that provides for customization of the background color and image.
In the Log Lolla case this means you can set a background image and the theme design won’t broke; however the aesthetics will suffer for sure.
Page backgrounds are never meant to improve a site’s design. They are an old technique which somehow survived into WordPress theme customisation requirements.
We recommend customizing the color scheme instead and leave the design as is without any custom background image.