% Fichier ex12.2.3-2.tex - Ch. Rolland/O Reilly France
\documentclass{article}
\usepackage[latin1]{inputenc}
\begin{document}
\newlength{\cadredim}
\setlength{\cadredim}{3cm}
\newcommand{\dblcadre}[1]{%
{\setlength{\fboxrule}{3pt}%
\setlength{\fboxsep}{2pt}%
\fbox{\setlength{\fboxrule}{1pt}%
\setlength{\fboxsep}{20pt}%
\fbox{\parbox{\cadredim}{#1}}}}}
\dblcadre{\centering\LaTeX\\par~la~pratique}
\end{document}
