How i can create this fancy header in lyx?

Question

Please how I can create fancy header like the header from page 7 and above in this book: Her

Answer 1

As the sources are online (e.g. here) you may compile the following into your preamble:

\documentclass{scrreprt}
\usepackage[svgnames]{xcolor}
\usepackage{geometry}
    \geometry{papersize={180mm,210mm},%
      includehead,includemp,reversemp,marginparwidth=4em,%
      vmargin={1.5mm,3mm},hmargin=1.75mm}%
\usepackage{scrlayer-scrpage}%
\makeatletter
    \clearpairofpagestyles
    \ihead{%
      \smash{%
        \hspace*{.5em}\rule[-\dp\strutbox]{0pt}{\headheight}\leftmark
      }%
    }%
    \ohead*{\smash{\pagemark\hspace{2mm}}}%
    \colorlet{headbackground}{DarkBlue}%
    \colorlet{headline}{white}%
    \setkomafont{pageheadfoot}{\small\sffamily\bfseries\color{headline}}%
    \setkomafont{pagenumber}{}%
    \DeclareNewLayer[head,background,
      hoffset=0pt,
      width=\paperwidth,
      addheight=\dimexpr \topmargin+1in+\dp\strutbox\relax,
      addvoffset=2\dp\strutbox,
      contents={%
        \color{headbackground}\rule{\layerwidth}{\layerheight}}]
    {headbackground}%
    \AddLayersAtBeginOfPageStyle{scrheadings}{headbackground}%
    \renewcommand*{\chaptermark}[1]{%
      \markleft{\ifnumbered{chapter}{\chaptermarkformat}{}#1}%
    }%
    \renewcommand*{\chaptermarkformat}{%
      \makebox[\dimexpr \oddsidemargin+1in-.5em][r]{%
        \chapapp~\thechapter:~%
      }%
    }%
    \renewcommand*{\chapterformat}{}%
    \renewcommand*{\chapterpagestyle}{scrheadings}%
    \setlength{\@tempdimc}{\oddsidemargin}%
    \addtolength{\@tempdimc}{1in}%
    \setheadwidth[-\@tempdimc]{paper}%
    \renewcommand*{\chapterheadstartvskip}{}%
\makeatother

\usepackage{blindtext}

\begin{document}
    \chapter{Test}
    \blinddocument
\end{document}

Answer 2

Thank You. I Test it, but not worked with me. I used this code:

\fancyhf{}
\fancyhead[LE,RO]{{\noindent\hspace*{\dimexpr-\oddsidemargin-1in\relax}%
 \colorbox{MidnightBlue}{\makebox[\dimexpr\paperwidth-2\fboxsep\relax]{
\textcolor{white}{\rightmark}}}}%
 \hspace*{-\paperwidth}}
\fancyhead[LO,LE]{\leftmark}

its worked but,

1- I can't use \noindent with :

fancyhead[LO,LE]{\leftmark}

2- the \rightmark in the center, i want it in the right side.