EDIT This is not a Venn diagram but an Euler diagram.
ORIGINAL QUESTION I want to draw a Venn Diagram for an absolute complement. However, I'm having problems with the background filling. The M circle needs to be without fill (white). How can I achieve that?
This is my Venn-diagram so far:
And this is the MWE:
\documentclass{scrbook}
\usepackage{tikz}
\usetikzlibrary{matrix,shapes,backgrounds,fit}
\usepackage{amssymb}
\begin{document}
\begin{tikzpicture}
\def\firstcircle{(0,0) circle (1.5cm)}
\def\secondcircle{(0:0.5cm) circle (0.8cm)}
\colorlet{circle edge}{red!50}
\colorlet{circle area}{red!20}
\tikzset{filled/.style={fill=circle area, draw=circle edge, thick},
outline/.style={draw=circle edge, thick}}
\setlength{\parskip}{5mm}
\begin{scope}
\fill[filled] \firstcircle;
\clip \secondcircle;
\end{scope}
\draw[outline] \firstcircle node [xshift=-20pt] {$G$};
\draw[outline] \secondcircle node {$M$};
\node[anchor=south] at (current bounding box.north) {$\overline{M}$};
\end{tikzpicture}
\end{document}