I found what looks like a typo, a missing period, in the built-in kepub stylesheet (highlighted in red, I've added some line breaks):
.KBHighlighting { background-color: #C6C6C6 !important; }
.KBStackKeyword, .KBSearchResult, .KBAnnotation,
.KBHighlighting
, KBAuthorAnnotation{ font-size: 100% !important; -webkit-text-combine: inherit !important; }
.KBSearchResult { background-color: #C6C6C6 !important; }
.KBStackKeyword a { color: black !important; }
.KBAuthorAnnotation, .KBAuthorAnnotationContinued { background-color: transparent !important; text-decoration: none !important; }
.KBStackKeyword[writingMode="horizontal-tb"] a { border-bottom: 1px solid black !important; }
.KBAuthorAnnotation[writingMode="horizontal-tb"], .KBAuthorAnnotationContinued[writingMode="horizontal-tb"] { border-bottom: 2px dotted black !important; }
I don't know what effect it has, if any. (I don't use annotations much.)
The `Fix kepub full-screen mode side bearing cut-off bug` patch fixes the typo, since that patch has to re-arrange that part of the stylesheet, but I'll include a seperate fix here for use without that patch, if anyone wants to test it.
Code:
<Patch>
patch_name = `Fix kepub annotations stylesheet typo`
patch_enable = `yes`
replace_bytes = DB456A, 20, 2E
</Patch>