I have a TikZ node positioned between two other nodes using fit:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{fit}
\pagestyle{empty}
\usepackage{parskip}
\newcommand{\mybox}[1]{
\begin{tikzpicture}
\node (t) [minimum width=.4\linewidth,anchor=north west,draw] at (0,5){box above};
\node (b) [minimum width=.4\linewidth,anchor=south west,draw] at (0,0){box below};
\node [fit=(t.south west) (b.north east), inner sep = 0, draw, align=flush left]{#1};
\end{tikzpicture}
}
\begin{document}
\mybox{
{\large Here we} have\newline some...
...somewhat {\bfseries longer arbitrary text} content.
}
\end{document}
Now I would like to vertically align the contents of the node at the top and also add some padding around the node contents. How can I do this?


