Does your plugin works for background url images in a css file

I am using your plugin for serving webp images. For now I have set the replace <img> tag with <picture> tag option, but your Replace img URL options seems good. I am using wp-rocket for caching and also using simply static to serve the site as a static page. I want the background images to get converted in webp too. Also im serving static site so do i need to run the bulk convert to make the files available so that the plugin can access the webp version?

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