% -*- coding: utf-8 -*-
\documentclass{beamer}

\usepackage[french]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{ae}
\usepackage{textpos}
\usepackage{appendixnumberbeamer}
\usepackage{tikz}
\usepackage{multicol}

\def\minor #1{{\small\color{gray} #1}}

\usetheme{ibisc}

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\title{Title}
\author{Author}
\institute{\color{gray}IBISC, Université d'Évry}
\date{date}

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\begin{document}

\frontbg

\begin{frame}
  \titlepage
\end{frame}

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\bodybg

\begin{frame}{Title}
  Content
\end{frame}

\end{document}