\documentclass{beamer}

\setbeamercolor*{palette primary}{use=structure,fg=yellow,bg=structure.fg}
\setbeamercolor*{palette secondary}{use=structure,fg=yellow,bg=structure.fg!75!black}
\setbeamercolor*{palette tertiary}{use=structure,fg=yellow,bg=structure.fg!50!black}
\setbeamercolor*{palette quaternary}{fg=yellow,bg=black}

\setbeamercolor*{sidebar}{use=structure,bg=structure.fg}
  
\setbeamercolor*{palette sidebar primary}{use=structure,fg=structure.fg!10}
\setbeamercolor*{palette sidebar secondary}{fg=white}
\setbeamercolor*{palette sidebar tertiary}{use=structure,fg=structure.fg!50}
\setbeamercolor*{palette sidebar quaternary}{fg=white}

\setbeamercolor*{titlelike}{parent=palette primary}

\setbeamercolor*{separation line}{}
\setbeamercolor*{fine separation line}{}

%\usecolortheme{orchid}
\setbeamercolor{block title}{use=structure,fg=yellow,bg=structure.fg!75!black}
\setbeamercolor{block title alerted}{use=alerted text,fg=white,bg=alerted text.fg!75!black}
\setbeamercolor{block title example}{use=example text,fg=white,bg=example text.fg!75!black}

\setbeamercolor{block body}{parent=normal text,use=block title,bg=block title.bg!10!bg}
\setbeamercolor{block body alerted}{parent=normal text,use=block title alerted,bg=block title alerted.bg!10!bg}
\setbeamercolor{block body example}{parent=normal text,use=block title example,bg=block title example.bg!10!bg}

%\useinnertheme[shadow]{rounded}
\setbeamertemplate{blocks}[rounded][shadow=true]
\setbeamertemplate{items}[ball]
\setbeamertemplate{sections/subsections in toc}[ball]
\setbeamertemplate{title page}[default][colsep=-4bp,rounded=true,shadow=true]
\setbeamertemplate{part page}[default][colsep=-4bp,rounded=true,shadow=true]
  
\setbeamercolor*{author in head/foot}{parent=palette tertiary}
\setbeamercolor*{title in head/foot}{parent=palette secondary}
\setbeamercolor*{date in head/foot}{parent=palette primary}

\setbeamercolor*{section in head/foot}{parent=palette tertiary}
\setbeamercolor*{subsection in head/foot}{parent=palette primary}

\defbeamertemplate*{footline}{infolines theme}
{
  \leavevmode%
  \hbox{%
    \begin{beamercolorbox}[wd=\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
      \usebeamerfont{author in head/foot}\insertshortauthor{}\hspace*{3em}\textit{ titrecourt{}}
      \hspace*{3em} date{}\hfill\hfill\hfill\hfill\hfill\hfill\hfill\hfill\insertframenumber{} / \inserttotalframenumber
   \end{beamercolorbox}}%
 \vskip0pt%
}

\defbeamertemplate*{headline}{infolines theme}
{
  \leavevmode%
  \hbox{%
    \begin{beamercolorbox}[wd=\paperwidth,ht=2.25ex,dp=1ex,center]{section in head/foot}%
      \usebeamerfont{section in head/foot}\insertsectionnavigationhorizontal{.9\paperwidth}{}{}
    \end{beamercolorbox}}%
  \vskip0pt%
}

\setbeamercolor*{institute}{fg=blue}

\setbeamersize{text margin left=1em,text margin right=1em}

\setbeamertemplate{navigation symbols}{}

\setbeamercolor{normal text}{bg=yellow!60}
 
\setbeamercolor*{footnote}{use=structure,fg=blue!40,bg=structure.fg}
\renewcommand{\footnoterule}{}

\setbeamertemplate{title page}[colsep=-4bp,rounded=true,shadow=true]

\defbeamertemplate*{title page}{mytitle}[1][]
{
  \vbox{}
  \vfill
  \begin{centering}
    {\usebeamercolor[fg]{titlegraphic}\inserttitlegraphic\par}
    \vskip2em
    \begin{beamercolorbox}[sep=8pt,center,#1]{title}
      \usebeamerfont{title}\Huge titre\par%
      \vskip0.25em%
      {\usebeamerfont{subtitle}\usebeamercolor[fg]{subtitle} soustitre\par}%
    \end{beamercolorbox}%
    \vskip1em\par
    \begin{beamercolorbox}[sep=8pt,center,#1]{author}
      \usebeamerfont{author}\insertauthor
    \end{beamercolorbox}
    \begin{beamercolorbox}[sep=8pt,center,#1]{institute}
      \usebeamerfont{institute}
      ENST Bretagne
    \end{beamercolorbox}
    \vskip5em\par
    \begin{beamercolorbox}[sep=8pt,center,#1]{institute}
      \usebeamerfont{institute}
      \scriptsize  type{} -- %
      code{} %
      --  numero{}%
      \hfill\hfill\hfill\hfill\hfill\hfill   date
    \end{beamercolorbox}
  \end{centering}
}

\title{Un titre}

\begin{document}

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

\section{une section}

\begin{frame}{Essai}
  \begin{itemize}
  \item item 1
  \item item 2
  \end{itemize}
\end{frame}

\section{une autre section}
\end{document}
