This is what I have in mind:
and I would like to know the simplest way to achieve this purely in CSS adding as little rigidity as possible.
I know it's easy to use float to push the red div left or right. It's also possible to do background on the blue div and simply center the red one as if the blue was empty.
But I need the text to wrap neatly around the red box, and I can also specify the exact dimensions of both boxes if needed.