Ok, like I said this is over my league. Like when you mention "poem" as an element to control some values, it's confusing cause I don't have poetry in my books so why is "poem" an element in css code ?
So I guess I'll stick with the basics of css and your sample code shows that this "svg" code is to be entered right after "body class" so I'll try that and see how it goes
And to answer your question I view my ebooks with "Reader for PC" it's the Sony soft to see epubs.