Modified responsiveImg.js to support css background. Set your css background to a spacer (so it doesn't load) and add attribute data-src to the html element with the large background's path. Then call something like $("[data-src]").responsiveImg({ srcAttribute:"data-src" });
Modified responsiveImg.js.php: minor optimization to avoid file system overhead.
Merge pull request #4 from reblutus/master

Added css background functionality