How to change paths to images in background during build?

Question

gulp.js

How to change paths to images in background during build?
For example, I'm doing a project in scss and there was such a problem.
Project structure:
-img
-style
-parts
page.scss
main.scss
In the page.scss file, the paths to the pictures are ../../img, and in the main.scss file ../img.
When assembling, you need everything to be of the form ../img.