First concept

node_modules/next/dist/build/webpack/loaders/resolve-url-loader/index.d.ts

@@ -0,0 +1,9 @@
+/**
+ * A webpack loader that resolves absolute url() paths relative to their original source file.
+ * Requires source-maps to do any meaningful work.
+ */
+export default function resolveUrlLoader(this: any, 
+/** Css content */
+content: string, 
+/** The source-map */
+sourceMap: any): Promise<void>;