[Ahu Lee]

I'm sorry I don't really think that my question has something to do with Sigil itself, but I'm not sure where I should post it and here it is:

I'm making an epub using Sigil and when I open it in ADE or Nook-for-PC to check how it looks I notice that the readers don't render CSS correctly, the way it is\looks in Sigil or my web-browser.
For example, the both use different sans-serif font (I have set Arial in the CSS), they also have some problems with Drop-Caps (they are kinda "off the grid"). And they don't render letter-spacing property at all.

I'm not very experienced with all this ebook creation stuff, so could you enlighten me on why this might happen or what I should and shouldn't expect from the readers? Would there be a difference in the way hardware readers handle my epub?

Thank you very much!