@howlermiller The CanIUse link is about support for the attribute, not styling it. Good find on the prefixes I missed though (though I assume the single colon works for FF19+ too, like :before does? ), Opera prefix seems missing.
@CrocoDillon Oh, you’re right. That’s my bad. Here’s the link I should have posted: Styling the HTML5 placeholder. That article has a nice little graph showing exactly what you can use where. Looks like `font-style` doesn’t work in Opera, Safari 3.1, or IE<10. But breakage wouldn't be a huge deal here, either.
And actually, I don’t think the single colon does work in FF19+. I just tested it in 21, and it certainly doesn’t work here, but the double colon does. Weirdness.
@chrisburton Wow. That’s really nice. I like that a lot. Great work!