OpenSUSE epub server side mime type

I have a Firefox addon to read epub’s. When I’m at Project Guttenberg and click on an epub it opens in Firefox and using the epub addon. But, if I click on the OpenSUSE epubs, Firefox tries to download the files instead.

I believe this is a server side mime type issue, and was wondering if it it could be added to the OpenSUSE servers.

OpenSUSE Ebooks:
Index of /ebooks112

FireFox EPUBReader:
https://addons.mozilla.org/en-US/firefox/addon/45281

Project Guttenberg (Sherlock Holmes epub):
The Adventures of Sherlock Holmes by Sir Arthur Conan Doyle - Project Gutenberg

Thank you.