How to center an image using quickbook (or a .css)

I've been trying to center (or at least shift off the left margin) images in a Quickbook generated document.

The Quickbook manual and 

http://www.sagehill.net/docbookxsl/ImageAlignment.html

suggests that

[$smiley.jpg [align center]]

should work  (as [$smiley.jpg [align right]] and the default [$smiley.jpg [align left]] do work).

But seems to have no visible effect (and produces align="middle" in the html, which is vertical and not horizontal alignment).

I conclude that this is no longer an html feature?

So I looked briefly at adding a margin, using a custom CSS, building on Boostbook.css, as I doing already but this is clearly not in
my current skill-set :-(

Any suggestions on how to do this?

How difficult can it be ;-)

Thanks

Paul






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Paul A. Bristow
Prizet Farmhouse
Kendal UK LA8 8AB
+44 (0) 1539 561830