How to rewrite relative paths of fonts and images in css files (Gulp.js)?

Question

Node.js

When building a css project - dependency files from bower_components refer to their images and fonts in relative path - how to rewrite paths to their absolute ones?
For example, at the input a file with the content:

.info{
    background: url(themes/assets/hello.png)
}

At the exit:

.info{
    background: url(/static/img/hello.png)
}

Also, I would like the URLs that refer to CDN resources not to change.
How to do it?