My e-book reader shows <em> text with teal color and I like it, it's better visible than italic and the font remains upright and readable, I doubt it will be comfortable to read lots of text in italic. I didn't notice any discrepancy with <i>. But for some reason <strong> doesn't override <em> and they multiply, though I saw it used once when an exclamation was repeated several times with increasing emphasis for extra dramatism.