No problem here. (and I learned something. The CSS -class rules are not as solid as I believed

)
I rather gathered that there was copyright issues, that you were being
very good about honoring the boards' rules
I always test on my reader (after all, that is the intended target

),
I am used to things that look great ('my way') in Sigil, Calibre-viewer, don't always look so good in ADE
I don't even toss in targeting a covert to another format