Hi there,
\chaptermark is used by
\chpter to set the mark(s) for this chapter. If you call it from within
\fancyhead, you're overwriting the current mark(s).
Use
\leftmark within
\fancyhead, instead.
Now, the page header on odd pages contains the chapter title (plus chapter's number & name), but not on the first page of a chapter: here, page style plain is used by default, because it lets the eye catch on a new chapter start easier, if something is missing (page header) on one page while leafing through the pages.
If you really want to change that, use
\fancypagestyle{plain}{}.
Now you can use your redefinition of
\chaptermark to get rid of chapter's number & name in the page header.
Put it all together:
Code: Select all
\documentclass[12pt,a4paper]{book}
\usepackage{polyglossia}
\usepackage{blindtext}
\setdefaultlanguage{english}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhead{}
\fancyhead[RO,LE]{\thepage}
\fancyhead[CE]{Title of the book}
%\fancyhead[CO]{\chaptermark}<-- \chaptermark has no place here. It is used to *set* the mark(s) for a chapter, not to get it.
\fancyhead[CO]{\leftmark}
\fancyfoot{}
\renewcommand{\chaptermark}[1]{\markboth{#1}{}}
\renewcommand{\headrulewidth}{0.4pt}
\renewcommand{\footrulewidth}{0pt}
\fancypagestyle{plain}{}%<-- only if you really want to have the first page of a chapter showing the same stuff like the chapter's title just below it...
\begin{document}
\chapter{Title of the chapter}
\blindtext[12]
\end{document}
KR
Rainer