[hulabula]

Hello,

I have created an e-book in which I would like to use an embedded font for some parts of the text.
I have the following in a css file:

@font-face {
font-family: "Open Sans";
font-weight: normal;
font-style: normal;
src: url(../Fonts/OpenSans-Regular.otf);
}

This is used as follows:

.sansserif {
font-family: "Open Sans", sans-serif;
}

I created the e-book with Sigil. The preview in Sigil works, it also works in Calibre. But when I copy the e-book to my Kobo reader (Aura H2O 2nd edition), only one font is used. Not the special one I embedded, and not the fallback sans-serif font, but the "default" serif font I use for all the other text in the book.
This is my first self-created e-book, and I don't have a different e-reader to test with. So I have no comparisons.

What could be the problem here?

Thanks for any help!