Background color for caution blocks in the Handbook

[Glen Barber]

Hi all,

While looking through the new HAST documentation in the Handbook, it
occurred to me that we don't have any special highlighting for 'caution'
tags.

I think maybe it would be good to have the caution sections stand out a
bit, since those sections might contain the makings of a foot canon if
the user is not careful.

Any thoughts before I go hacking away at the CSS?

Regards,

-- 
Glen Barber | gjb at FreeBSD.org
FreeBSD Documentation Project