\documentclass{article}
\usepackage{web}
\margins{0pt}{0pt}{0pt}{0pt}   %% Kein Seitenrand
\screensize{280mm}{370mm}      %% Dimensionen: H\"{o}he, Breite des Dokuments

\parindent0pt

\usepackage{pstricks,pstricks-add}

\definecolor{denmarkRed}{HTML}{FF173D} %Pantone 185 


\begin{document}

\thispagestyle{empty}

\begin{pspicture}(0,0)(37,28)
%% Flagge (Verh\"{a}ltnis 37 Breite : 28 H\"{o}he)
%% Breite 12 - 4 - 21 : H\"{o}he 12 - 4 - 12
\psframe[linecolor=denmarkRed,fillstyle=solid,fillcolor=denmarkRed](0,0)(37,28)
\pspolygon[linecolor=white,fillstyle=solid,fillcolor=white](0,12)(12,12)(12,0)(16,0)(16,12)(37,12)(37,16)(16,16)(16,28)(12,28)(12,16)(0,16)
\end{pspicture}
\end{document}
