How to avoid that the styles of a node style pass in a schema included in the node
thus on the ECM below, the node of right becomes green and is cut in 2 and that of left does not change of color but is cut off
\documentclass{standalone}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{fit, positioning}
\usetikzlibrary{shapes.multipart}
\begin{document}
\tikzset{rougelarge/.style={fill=red!20,minimum width=15em,minimum height=4em,text width=15em,draw}}
\newcommand{\nodeUn}{
\begin{tikzpicture}
\node[rougelarge](aa){texte sur plusieurs lignes\\texte sur plusieurs lignes};
\node[right=5em of aa,draw](bb){texte};
\end{tikzpicture}
}
\begin{tikzpicture}
\node[rectangle split, rectangle split parts=2,fill=green]{texte sur plusieurs lignes
\nodepart{two}
\nodeUn
};
\end{tikzpicture}
\end{document}



