Can anyone explain why this simple table comes out skewed?
\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\begin{tikzpicture}[
]
\matrix (m) [matrix of nodes, nodes in empty cells,
nodes = {minimum width=1cm,},
column 4/.style={minimum width=8cm},
]
{
Sr & Drug & Dose & Frequency & Duration & Remark \\
1 & & & & & \\
2 & & & & & \\
3 & & & & & \\
4 & & & & & \\
5 & & & & & \\
6 & & & & & \\
7 & & & & & \\
};
\foreach \c in {1,...,6}
\draw [gray] (m-1-\c.north east) -- (m-8-\c.south east);
\draw (m-1-1.south west) -- (m-1-6.south east);
\draw (m-8-1.south west) -- (m-8-6.south east);
\foreach \r in {2,...,7}
\draw [dotted, blue] (m-\r-1.south west) -- (m-\r-6.south east);
\end{tikzpicture}
\end{document}



column 6/.style={nodes={minimum width=8cm},. – Rmano Feb 19 '17 at 13:31matrix. I used it to propose a kind of "form" in http://tex.stackexchange.com/questions/354463/how-to-make-hline-in-table-print-fainter – Rmano Feb 19 '17 at 19:17