I considered doing this in a story I've written. “Never stopped anybody from….” But then I realised it was stupid and my writing was perfectly capable for showing that the speaker trailed off, without font size changes. People are perfectly capable of understanding what blood is, without a visual reminder.
On two occasions I've portrayed a character looking at backwards words by inserting an image of the text he was looking at, backwards. A professor thought it was really cool, so there's that.
Yeah, and House of Leaves does this as well, in addition to numerous other font and formatting tricks. It worked for that book.
The issue I'm concerned with is submitting the manuscript. Most companies want Times of Courier, and no images added. My guess is that I would make some kind of inline comment. Kind of a head scratcher there.
Yeah, I don't know. Would be interesting to know how Danielewski submitted House of Leaves, particularly since it was a first novel. Seems like he would have submitted it with all the font and formatting tricks intact, since they're integral to the book.
I think it really comes down to finding an agent and a publisher that is willing to take a risk on you. And then succeeding despite the risks. That's also a part of it.
For me, it would definitely have the opposite effect--it would pull me out of immersion in the story.
I've read books where the author stuck a company notice or news article in the story with the notice/article had different formatting than the rest of the novel.