Missing Palatino font for chapters.
Using the KCSS-style with the Palatino font generates the warning
LaTeX Font Warning: Font shape `T1/pplx/bx/sc' undefined
(Font) using `T1/pplx/bx/n' instead on input line ...
It appears to be the font that is used for the "Chapter " texts. This font can be substituted manually using
\DeclareFontShape{T1}{pplx}{bx}{sc}{<->ssub*jkp/bx/sc}{}
or a similar option.