\usepackage{tikz}

% set fonts
\setbeamerfont{title}{size=\huge}
\setbeamerfont{author}{size=\large}
\setbeamerfont{institute}{size=\small}
\setbeamerfont{date}{size=\footnotesize}
\setbeamerfont{frametitle}{size=\huge}

\setlist[itemize]{
    itemsep=0.25cm,
    label={{\footnotesize$\bullet$}}
}

\def \tuxgaucho {images/Tuxgaucho.png}

% Adiciona tux gauderio a todos os slides
\usebackgroundtemplate{
    \includegraphics[width=2cm]{\tuxgaucho}
}

% Centraliza os títulos dos slides.
\setbeamertemplate{frametitle}[default][center]

\renewcommand{\coverframe}{%
    {%
        \usebackgroundtemplate{%
            \tikz\node[opacity=0.2]%
                {\includegraphics[width=1.05\paperheight]{\tuxgaucho}};%
        }%
        \begin{frame}%
            \titlepage%
        \end{frame}%
    }%
}

\renewcommand{\finalframe}[2][Thank you!]{%
    {%
        \usebackgroundtemplate{%
            \includegraphics[width=1.05\paperheight]{\tuxgaucho}%
        }%
        \begin{frame}%
            \begin{flushright}%
                \huge \textbf{#1}%
                \vfill%
                \large \textbf{#2}%
            \end{flushright}%
        \end{frame}%
    }%
}

\renewcommand{\bigtitle}[1]{%
    {%
        \usebackgroundtemplate{%
            \tikz\node[opacity=0.2]%
                {\hspace*{7cm}\includegraphics[width=.95\paperheight]{\tuxgaucho}};%
        }%
        \begin{frame}%
        \begin{center}\huge{#1}\end{center}%
        \end{frame}%
    }%
}
