The zip file I tried to upload was 6MB including 1 KFX and 2 EPUBs.
I got the book from Amazon Japan. The ASIN is B01EUC17SW.
Caliber creates the pargraph tag like theis:
<p class="class_sf">
.class_sf {
display: block;
margin: 0;
}
"From KFX" creates the paragaph tag like this:
<p class="class_sF">
.class_sF {margin-bottom: 0; margin-top: 0}
I changed "margin-bottom" to "margin-left" and "margin-top" to "margin-right". After these changes, the EPUB was displayed correctly.