Specifying font size in a \newcommand?

Question

I'm typing up a document in which I'd like to the margin's note font to be footnote size. This is my code:

\documentclass[12pt]{article}
\usepackage{outlines,marginnote}
\usepackage[top=1cm, bottom=1.3cm, left=5cm, right=0.75cm, heightrounded, marginparwidth=4.6cm, marginparsep=3mm]{geometry}
\reversemarginpar
\newcommand{\mn}{\marginnote}
\pagestyle{empty}

\begin{document}
\begin{flushleft}
\Large \underline{Chapter 8 \textsc{Lipids}}  
\end{flushleft}

\section*{Lipids}
\begin{outline}[enumerate]
  \1 What is a lipid? \mn{{\footnotesize How's it different from the other functional groups?}}
\end{outline}

\end{document}

As it can be seen from my MWE, I had to specify the font size while making the margin note, but I want \footnotesize to assumed automatically. I'm thinking this can be done by modifying my \newcommand for margin note. I tried playing around with it, but nothing worked. If anyone could point me in the right direction, I'd really appreciate it.

Answer 1

The documentation of marginnote is your friend:

\renewcommand*{\marginfont}{\footnotesize}

Here is a complete example:

\documentclass[12pt]{article}
\usepackage{marginnote,letltxmacro}
\renewcommand*{\marginfont}{\footnotesize}
\LetLtxMacro\mn\marginnote
\pagestyle{empty}

\begin{document}
 What is a lipid? \mn{How's it different from the other functional groups?}
\end{document}

With the package outlines.sty it also works:

\documentclass[12pt]{article}
\usepackage{outlines,marginnote,letltxmacro}
\usepackage[top=1cm, bottom=1.3cm, left=5cm, right=0.75cm, heightrounded, marginparwidth=4.6cm, marginparsep=3mm]{geometry}
\reversemarginpar
\renewcommand*{\marginfont}{\footnotesize}
\LetLtxMacro\mn\marginnote
%\newcommand{\mn}{\marginnote}
\pagestyle{empty}

\begin{document}
\begin{flushleft}
\Large \underline{Chapter 8 \textsc{Lipids}}  
\end{flushleft}

\section*{Lipids}
\begin{outline}[enumerate]
  \1 What is a lipid? \mn{{\footnotesize How's it different from the other functional groups?}}
\end{outline}

\end{document}

EDIT Added letltxmacro. Thanks to Werner for his comment.

Answer 2

You could try \newcommand{\mn}[1]{\marginnote{\footnotesize #1}}. That would work, but Marco's solution is better.