Still, I like the OP's original aim and I don't see any reason to skip past it.
Here's a version using no special CSS at all <g>, working back to IE
7.
http://jsfiddle.net/sanford/KTcmG/15/
Note the opacity of the mask is left as an exercise to the reader.
Obviously, that is something the OP already knows how to do.
-- S.
