I have a question about commas after italics.
In The Elements of Typographic Style, Robert Bringhurst wrote the following:
"When boldface is used to empasize words, it is usually best to leave the punctuation in the background, which is to say, in the basic text fonts. It is the words, not the punctuation, that merit emphasis in a sequence such as the following:
(…)
But if the same names are emphasized by setting them in italic, rather than bold, there is no advantage in leaving the punctuation in roman. With italic text, italic punctuation normally gives better letterfit and thus looks less obtrusive:"
However, other sources are of a different opinion. International Reading Association for example writes the following:
"Commas, italic and roman
1. A comma that falls within a title or other italicized matter should be set in italics.
• C.S. Lewis’s novel The Lion, the Witch, and the Wardrobe (1950) is an allegory.
2. A comma that falls between items in italics should be set in roman.
• C.S. Lewis’s allegorical trilogy comprises the novels Out of the Silent Planet, Perelandra, and That Hideous Strength.
Exception: In text published in HTML, punctuation that immediately follows an italicized word or phrase should also be set in italics."
My question is, naturally, what is right. Should the comma after an italized word be italized or not?
Regards,
Viktor Grut
(I made a search but couldn't come up with anything about this. If there is already a post about this, please forgive me and direct me to that post.)

