margins with landscape and page header

Question

I use the scrreprt class with a page header. I also use margin notes. It looks good in portrait mode. However, some pages may be rotate. In that case, this looks ugly. Here is a MWE:

\documentclass[a4paper]{scrreprt}

\usepackage{lipsum}
\usepackage{pdflscape}
\usepackage[headsepline]{scrlayer-scrpage}
\pagestyle{scrheadings}
\clearscrheadings
\ohead{\pagemark{}}

\newcommand{\examplepage}{
  \lipsum[1]
  \marginpar{This is a marginal note.}
  \lipsum[2-4]
}

\begin{document}
\examplepage{}

\begin{landscape}
\examplepage{}
\end{landscape}

\end{document}

What can I do to improve the page layout in landscape?

Answer 1

You can use \reversemarginpar inside the landscape environment:

\documentclass[a4paper]{scrreprt}

\usepackage{lipsum}
\usepackage{pdflscape}
\usepackage[headsepline]{scrlayer-scrpage}
\pagestyle{scrheadings}
\clearscrheadings
\ohead{\pagemark{}}

\newcommand{\examplepage}{
  \lipsum[1]
  \marginpar{This is a marginal note.}
  \lipsum[2-4]
}

\begin{document}
\examplepage{}

\begin{landscape}
\reversemarginpar
\examplepage{}
\end{landscape}

\end{document}