Properly aligning and wrapping image captions

Easily align and wrap captions to images of unknown size with two relatively unknown CSS properties.

I recently learned a new css trick to align and wrap captions properly to images of unknown size.  This is a common problem when dealing with any content management system that allows users to upload images to pages or articles.

The problem:

This is a caption of slightly longer length. It should wrap, regardless of the size of the image.

The css solution:

This is a caption of slightly longer length. It should wrap, regardless of the size of the image.

Voilà!