<i>, <em> and font-style:italic in HTML 5

Hello, 
 
Upon the HTML 5 standards, http://www.w3.org/TR/2012/CR-html5-20121217/text-level-semantics.html#the-em-element
The i element represents a span of text in an alternate voice or mood.
The em element represents stress emphasis of its contents.
 
I believe a class with style="font-style:italic" would be like using an i element to alternate voice or mood without emphasis. 
Is that correct?
 
Thank you,
Rabab