I wanted to set my latest book in a sans-serif font so I chose one of iBooks' default fonts: Seravek. This morning, doing a last minute check, Seravek had mostly disappeared. I immediately suspected nefarious setting adjustments by iPad-stealing family members, but it turns out iBooks was the culprit.
Look at this:
If you don't know what Seravek is, I'll tell you, it's not that.
I recompiled my book a bunch of times, looked at it on my old iPad and everywhere, the font had disappeared. I wondered if iBooks had somehow changed between yesterday and today. If Kindle Previewer was going to update itself without my involvement, maybe iBooks too?
Then I changed the font size:
And the Seravek came back. Weird. It turns out that Seravek works fine in all font sizes except 5. And in font size 3, it doesn't work in the subhead, but I wonder if that has to do with caching, since I had that set as a serif font for a while (though not in this example!)
Since there's no other sans-serif default font for iBooks, and I didn't want to use Optima, in the end, I decided on Muli, one of Google Web Fonts offerings:
Remember that readers can always select a default font if they so choose.