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Hello

Can someone help me cut this brown area, so it is only inside the dashed lines? :-)

\documentclass{memoir}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
\draw[style=help lines] (-0.5,-0.2) grid (8,6.5);
\centering
\clip(-0.5,-0.2) rectangle (8,6.5);
\draw[black,very thick ...