LaTeX Forum

\documentclass[paper=a4,fontsize=12pt,numbers=noenddot]{scrbook}
\usepackage[margin=2.5cm]{geometry}

\renewcommand\normalsize{\@setfontsize\normalsize{12}{14.4}}
\renewcommand\large{\@setfontsize\large{14}{16.8}}
\renewcommand\LARGE{\@setfontsize\LARGE{18}{21.6}}
\renewcommand\huge{\@setfontsize\huge{20}{24}}

\newcommand{\chapnumsize}{\LARGE}
\newcommand{\chapnumstyle}{\normalfont\mdseries}
\newcommand{\chapsize}{\huge}
\newcommand{\chapstyle}{\mdseries}
\newcommand{\secsize}{\large}
\newcommand{\secstyle}{\mdseries}

\addtokomafont{part}{\mdseries}
\addtokomafont{partnumber}{\mdseries}
\addtokomafont{chapter}{\mdseries}
\addtokomafont{section}{\mdseries}

\setkomafont{disposition}{\normalcolor\bfseries}

\ifnumbered{chapter}{then...}{else...}
\ifunnumbered{chapter}{then...}{else...}

\begin{document}

\section*{Acknowledgements}
This project consumed huge amount of work, research and dedication. Still, implementation would not have been possible if we did not have a support of many individuals and organizations.


\chapter{Chapter Heading}
\section{Section Heading}
This is the same text as before, as this project consumed huge amount of work, research and dedication. Still, implementation would not have been possible if we did not have a support of many individuals and organizations.

This is the same text as before, as this project consumed huge amount of work, research and dedication. Still, implementation would not have been possible if we did not have a support of many individuals and organizations.

\end{document}

\@ and @ in macro names

\documentclass[paper=a4,fontsize=12pt,numbers=noenddot]{scrbook}
\usepackage[margin=2.5cm]{geometry}

\makeatletter
\renewcommand\normalsize{\@setfontsize\normalsize{12}{14.4}}
\renewcommand\large{\@setfontsize\large{14}{16.8}}
\renewcommand\LARGE{\@setfontsize\LARGE{18}{21.6}}
\renewcommand\huge{\@setfontsize\huge{20}{24}}
\makeatother

\newcommand{\chapnumsize}{\LARGE}
\newcommand{\chapnumstyle}{\normalfont\mdseries}
\newcommand{\chapsize}{\huge}
\newcommand{\chapstyle}{\mdseries}
\newcommand{\secsize}{\large}
\newcommand{\secstyle}{\mdseries}

\addtokomafont{part}{\mdseries}
\addtokomafont{partnumber}{\mdseries}
\addtokomafont{chapter}{\mdseries}
\addtokomafont{section}{\mdseries}

\setkomafont{disposition}{\normalcolor\bfseries}

%%\ifnumbered{chapter}{then...}{else...}
%%\ifunnumbered{chapter}{then...}{else...}

\begin{document}

\section*{Acknowledgements}
This project consumed huge amount of work, research and dedication. Still, implementation would not have been possible if we did not have a support of many individuals and organizations.


\chapter{Chapter Heading}
\section{Section Heading}
This is the same text as before, as this project consumed huge amount of work, research and dedication. Still, implementation would not have been possible if we did not have a support of many individuals and organizations.

This is the same text as before, as this project consumed huge amount of work, research and dedication. Still, implementation would not have been possible if we did not have a support of many individuals and organizations.

\end{document}

\documentclass[paper=a4,fontsize=12pt,numbers=noenddot,chapterprefix]{scrbook}
\usepackage[margin=2.5cm]{geometry}

% Keine Ahnung, was die Umdefinierung soll, aber damit sie funktioniert,
% muss man sie korrekt mit \makeatletter…\makeatother klammern.
\makeatletter
\renewcommand\normalsize{\@setfontsize\normalsize{12}{14.4}}
\renewcommand\large{\@setfontsize\large{14}{16.8}}
\renewcommand\LARGE{\@setfontsize\LARGE{18}{21.6}}
\renewcommand\huge{\@setfontsize\huge{20}{24}}
\makeatother

% Das wird nirgendwo verwendet und kann deshalb weg:
%\newcommand{\chapnumsize}{\LARGE}
%\newcommand{\chapnumstyle}{\normalfont\mdseries}
%\newcommand{\chapsize}{\huge}
%\newcommand{\chapstyle}{\mdseries}
%\newcommand{\secsize}{\large}
%\newcommand{\secstyle}{\mdseries}

% Überall \mdseries hinzuzufügen ist Unfug. Laut Abbildung sollen die
% Überschriften fett bleiben. Also wäre \mdseries ohnehin falsch. Ansonsten
% würde man einfach bei disposition das \bfseries weg lassen und gut.
%\addtokomafont{part}{\mdseries}
%\addtokomafont{partnumber}{\mdseries}
%\addtokomafont{chapter}{\mdseries}
%\addtokomafont{section}{\mdseries}

\setkomafont{disposition}{\normalcolor\bfseries}
% Dann setzen wir die Größe der Überschriften:
\setkomafont{chapter}{\huge}% entsprechend der obigen Umdefiniererei 20pt
\setkomafont{chapterprefix}{\LARGE}% entsprechend der obigen Umdefiniererei 18pt
\setkomafont{section}{\large}% entsprechend der obigen Umdefiniererei 14pt
\setkomafont{subsection}{\itshape}% nur kursiv
% Jetzt noch der riesige Abstand nach der Kapitelüberschrift
\RedeclareSectionCommand[afterskip=160pt]{chapter}

% Nachfolgendes ist kompletter Unfug, da die entsprechenden Anweisungen nur
% innerhalb bestimmter anderer Befehle definiert sind. Also streichen wird
% das:
% \ifnumbered{chapter}{then...}{else...}
% \ifunnumbered{chapter}{then...}{else...}

\usepackage{mwe}% siehe Minimalbeispiel-Anleitung

\begin{document}

\chapter*{Acknowledgements}
\lipsum[1]
\chapter{Chapter Heading}
\lipsum[2]
\section{Section Heading}
\lipsum[3]
\subsection{Subsection Heading}
\lipsum[4]

\end{document}