Highlight a file's layer (e.g. using Clean Architecture)

We are building a small Java service using just 3 layers of Uncle Bob's "clean architecture", and its still easy to get lost while navigating through the layers. Each layer has its own package under src/main (with multiple subpackages) and I often am checking the file path to see which layer I am currently in. I would like to be highlighted more obviously to help me and more junior colleagues.

Is there a way to e.g. configure the colour of the editor background or other IDE elements to change depending on a file's position in the package hierarchy? If not is there another way to approach this - e.g via a plugin?

Thanks for any help you can provide with this :)