\usepackage{titlesec}
\usepackage[many]{tcolorbox}


\providecommand*{\DUdocumentsubtitle}[1]{{\EBLigatures\selectfont\em\LARGE\begin{flushright}#1\end{flushright}}}

\makeatletter

%\def\@subtitle{\relax}
\newcommand{\subtitle}[1]{\gdef\@subtitle{#1}}

\def\@maketitle{%
  \begin{tcolorbox}[colback=sidecolor, sharp corners]
  \begin{center}
    \vspace*{1cm}
    \textcolor{white}{\fontsize{1.2cm}{2cm}\CaviarDreamsFont\selectfont \@title}
  \end{center}
  \vspace*{1cm}
  \end{tcolorbox}
}
\makeatother


\newcommand{\periodafter}[1]{#1.}

% Titre de niveau 1
\titleformat{\section}
  {\CaviarDreamsFont\selectfont\Large\centering}
  {\thesection}
  {0em}
  {\vspace{1cm}}
  []

% Titre de niveau 2
\titleformat{\subsection}
  {\large}
  {\thesubsection}
  {}
  {\textcolor{black!69}}

% Titre de niveau 3
\titleformat{\subsubsection}
  {\bfseries\normalsize}
  {\thesubsubsection}
  {2em}
  {}
  {}

\newcommand{\DUtitletitle}[1]{%
  \begin{tcolorbox}[colback=sidecolor, sharp corners]%
  \begin{center}%
  \begin{CaviarDreamsBoldFont}%
      {\textbf\selectfont\color{white}{\scriptsize\uppercase{#1}}}%
  \end{CaviarDreamsBoldFont}%
  \end{center}
  \end{tcolorbox}
 }

\let\oldtitle\maketitle
\renewcommand{\maketitle}{%
  {\oldtitle}
  \begin{paracol}{2}
}