@jackie_w: To replace "OEBPS" by ".." has been my first reaction, but it had no result, as well as other variants that I tried, for ex. leaving away "OEBPS" or ".." and beginning immediately with "Fonts", as you suggest.
The possibility of using the "Arrange folders" option has been until now unknown to me (thanks for the hint!). I tried it with a book where the adding of my font had worked (by working out in Sigil and re-opening in Calibre), and in the "Arrange folders" option, the sub-directory is "fonts", whereas in the page-style-css, I have "OEBPS/
Fonts"; I saw books in Calibre with "
fonts" in the page-style-css, and everything was working. So, I doubt if Calibre is really so strongly case-sensitive. But thank you for your support!
@Kovid: I forgot to mention, sorry! But I had pressed the "Embed all fonts" button.
Could it be that the name of the font causes the problems, by any characters that are difficult to handle, perhaps?
@jackie_w: I just tried it once more, with the help of your suggestion ("Arrange folders"). After clicking "OK", the declaration in the page-style-css changed to
Code:
src: url(../../fonts/FoglihtenNo07_0841.otf);
, and this did the trick! After running "Check book", no problem was reported.
I've no idea from where comes the double subdirectory, but I'm glad now!
Many, many thanks to all!