I wrote my diploma thesis in a one-sided layout (report) and now I want to print it, but don't want to have the back page blank on every single page. So I want to change the paper format to a two-sided layout in order to have a different offset on odd and even pages. For that reason, I changed my preamble which looks like this now:
\documentclass[a4paper, 12pt, twoside, openright]{report}
\usepackage[showframe]{geometry}
\usepackage{lipsum}
\usepackage{ngerman}
\usepackage{fancyhdr}
\usepackage{a4}
\usepackage{setspace}
\usepackage{graphicx}
\usepackage{sectsty}
\makeatletter
\renewcommand*\l@section{\@dottedtocline{2}{3.8em}{4em}}
\renewcommand*\l@subsection{\@dottedtocline{2}{3.8em}{4em}}
\renewcommand*\l@subsubsection{\@dottedtocline{2}{3.8em}{4em}}
\renewcommand*\l@figure{\@dottedtocline{1}{2.8em}{3em}}
\renewcommand*\l@lstlisting{\@dottedtocline{1}{2.8em}{3em}}
\makeatother
\parindent=0pt
\parskip=12pt
\onehalfspacing
\setlength{\headheight}{15pt}
\addtolength{\textwidth}{1.5cm}
\begin{document}
\pagestyle{fancyplain}
\renewcommand{\sectionmark}[1]{\markright{\thesection\ #1}}
\renewcommand{\chaptermark}[1]{\markright{\thechapter\ #1}}
\lhead[\fancyplain{}{\sffamily\sl\thepage}]{\fancyplain{}{\sffamily\sl\rightmark}}
\rhead[\fancyplain{}{\sffamily\sl\leftmark}]{\fancyplain{}{\sffamily\sl\thepage}}
\cfoot{}
\lipsum[1-100]
\end{document}
When I compile it, the following PDF is generated:
Obviously, the offset is the wrong way around. Page 1 should have the offset of page 2 and inverse. Does somebody know a simple solution for this problem?