How to Apply CSS3 Transforms to Background Images - SitePoint
Briefly

CSS transformations commonly rotate the entire element, including content and background. A CSS-based workaround allows independent transformation of background images via pseudo elements.
Currently, CSS lacks a W3C proposal for transforming background images, creating challenges for developers. The workaround uses the ::before or ::after pseudo elements to achieve desired effects.
Read at Sitepoint
[
|
]