Motivated by the sudden appearance of the "Add to home screen" prompt, I spent the last couple of hours to tune my Service Worker / caching behaviour:

- I can now exclude parts of my site from the service worker. This was an important feature for me, since the WordPress backend didn't sit too well with stubborn cached items.

- I established a number of caches for different items:
-- a "static" cache that has the base css and the page that gets displayed when the network is offline.
-- a "content" cache, that stores up to 25 URLs a visitor has, well, visited, while being online.
-- an "image" cache, that stores up to 45 image files, and finally
-- an "asset" cache for up to 35 files (everything that is not HTML and not an image).

The limits are rather random, but I think each cache has an build-in maximum of 50 entries (?), so to see if it works, I choosed numbers smaller than that.