I'm using 'Suffusion 4.0.4' to build a site for a friend (http://www.instituteofchairmans.com)
Thank you all for detailing how to set up a child theme, that has been successful...ish.
For reasons which I don't understand, activating the child theme causes the nav bar under the header to disappear. I can't think of any reason why this should happen.
Another problem, which I solved easily enough, was that the main wrapper had a green outline and light green background when i switched to the child theme. Solved, with a patch of css in the child folder, but still no idea why something as apparently random as this should happen.
The css for the child theme is as follows (short enough to put here I hope...)
sidebar shell and header container bits are fine. Commenting them out doesn't magically bring the missing nav bar back though...