This modification would be too complex, it would require virtual entries that could lead to different files depending on the user profile.

On solution would be to have separate folders for different formats. But this is not possible if you use Calibre to manage your collection.

Another solution (which is not ideal but would work) would be to have two instances of Ubooquity running (don"t forget to use different port numbers).

By using the "scan exclusion pattern" in the advanced options, one instance would exclude epubs files (use the pattern ".*.epub", without quotes ) and display only mobi, and the other one would do the opposite (".*.mobi").

That's something I had planned from the start. So it'll be definitely done someday. I just don't know when yet.

I understand, but it will have to wait for a hypothetical complete "templatization" of Ubooquity (allow users to fully customize pages structure in addition to the CSS).

Server side bookmarks (allowing you to resume reading on a different device) are still planned and are quite high on my todo list.

Read/unread flag will be a side effect of this development.

You can expect it this year.

Thanks for the feedback !

I found a bug related to fonts which happens only in Firefox, not in Chrome.

I don't know yet if it explains your problem, but there is definitely something to fix.

Probably before summer.

Just in case: your font files are actually woff files, not ttf files ?

Also, could you open your javascript console (F12 in yout browser) and check if there is any error when you change fonts to Open Sans ?

Yep.