In reply to Morten Rand-Hendriksen.

This is fairy tail ideal world. In real world nothing works that way.

I currently work on a top premium theme, ultra recent and from one of best themes companies out there that certainly can't be suspected of providing poorly coded themes.
Images appearing in category and archive listings have all nice borders and I certainly don't want to change this. But when I create a post/page and insert an image in the middle of the text there is absolutely no formatting - and that's correct because this should be customized case by case, because there is no general rule possible here.

In other words, please let me know how, in your ideal world, you would design a CSS that does the following:
- insert a 1px black border to images that have a white/light background and that are inserted in a page with a white/light background
- insert a 1px white border to images that have a black/dark background and that are inserted in a page with a black/dark background