[ldolse]

There is a sub-forum dedicated to epub authoring, you would get a lot more help there. I'm curious as to the answer to your question myself - I suspect that support for this type of function may not be great, but I'd love to be proven wrong.

BTW, this isn't even properly readable in Calibre on my system - I only see the spanish. It does look ok in Firefox. ADE also looks bad, and this means most of the hardware reading systems won't display either - they use ADE as their underlying engine.