[spacebrew]

I'll just post my whole CSS so you can check it out. The very bottom entry is the one I added that made it work though.

@font-face {
 font-family: "Nimbus";
 font-weight: normal;
 font-style: normal;
 src: url(res:///Data/fonts/Nimbus.ttf);
 }

 @font-face {
 font-family: "Nimbus";
 font-weight: normal;
 font-style: italic;
 src: url(res:///Data/fonts/Nimbus_I.ttf);
 }

 body {
 font-family: "Nimbus"; 
 } 

 p { 
 font-size: 1.0em !important;
 text-align: justify !important;
 line-height: 130% !important;
 text-indent: 1.5em !important;
 margin-top: 0.1em !important; 
 margin-bottom: 0.1em !important; 
 }

 html { 
 font-family: Nimbus !important;
 }

 .mainBody {
 font-family: Nimbus !important;
 }

 .calibre {
 font-family: Nimbus !important;
 }
 
 .epub {
 font-family: Nimbus !important;
 }

I might also add that some books just don't change with it though. A couple of them, I've had to go into the embedded css and remove the font-family lines so it will use the default. You might try that, and even remove the fonts folder from the epub file.