Como reduzir globalmente a largura do conteúdo em quadros no beamer?

Gostaria de diminuir a largura do conteúdo nos quadros em uma apresentação do projetor. Por enquanto, estou fazendo isso usando um ambiente de minipágina em cada quadro. Existe uma maneira de reduzir globalmente essa largura para evitar reduzir manualmente a largura em cada quadro?

\documentclass[9pt,trans,xcolor={table},envcountsect]{beamer} % Plain

\usefonttheme[onlymath]{serif}
\usetheme[shownavsym,right]{Aalborg}

\setbeamertemplate{section in toc}[sections numbered] % Automatic enumeration of sections
\setbeamertemplate{blocks}[rounded][shadow=true] 

\definecolor{dgreen}{rgb}{0.,0.6,0.} 
\definecolor{aaublue}{RGB}{33,26,82}% dark blue

\usepackage{etoolbox} % In order to still use an outdated beamer version

\AtBeginEnvironment{theorem}{%
\setbeamertemplate{itemize items}[circle]                    % Shape of bullet-points
\setbeamercolor{block title}{bg=dgreen!100!white,fg=white}%
\setbeamercolor{itemize item}{fg=dgreen!100!white}%
\setbeamercolor{itemize subitem}{fg=dgreen!100!white}%
\setbeamercolor{itemize subsubitem}{fg=dgreen!100!white}%
\setbeamercolor{enumerate item}{fg=dgreen!100!black}%
\setbeamercolor{enumerate subitem}{fg=dgreen!100!black}%
\setbeamercolor{enumerate subsubitem}{fg=dgreen!100!black}%
}

\AtBeginEnvironment{definition}{%
\setbeamertemplate{itemize items}[circle]                    % Shape of bullet-points
\setbeamercolor{block title}{bg=blue,fg=white}%
\setbeamercolor{itemize item}{fg=blue}%
\setbeamercolor{itemize subitem}{fg=blue}%
\setbeamercolor{itemize subsubitem}{fg=blue}%
\setbeamercolor{enumerate item}{fg=blue}%
\setbeamercolor{enumerate subitem}{fg=blue}%
\setbeamercolor{enumerate subsubitem}{fg=blue}%
}

\setbeamercolor*{block body}{bg=black!10!white,fg=black} 
\setbeamercolor*{block body alerted}{bg=normal text.bg!90!black,fg=black} 
\setbeamercolor*{block body example}{bg=normal text.bg!90!black,fg=black} 
\setbeamercolor*{block title}{parent=structure2,bg=normal text.bg!0!blue}
\setbeamercolor*{block title alerted}{use={normal text,alerted text},fg=alerted text.fg!0!white,bg=normal text.bg!10!red}
\setbeamercolor*{block title example}{use={normal text,example text},fg=white,bg=cyan}
\setbeamercolor*{block title theorem}{use={normal text,example text},fg=example text.fg!100!normal text.fg,bg=normal text.bg!0!dgreen}

\makeatletter
\pgfdeclareverticalshading[lower.bg,upper.bg]{bmb@transition}{200cm}{color(0pt)=(lower.bg); color(4pt)=(lower.bg); color(4pt)=(upper.bg)}
\makeatother

\setbeamertemplate{theorems}[numbered]
\addtobeamertemplate{theorem begin}{\normalfont}

\let\definition\undefined
\newtheorem{definition}{\translate{Definition}}[section]


\begin{document}

\begin{frame}[<+->]{Globally shrink the frame width}
    \begin{minipage}{0.89\textwidth}
        \begin{definition}
            \begin{itemize}
                \item Wanted: Reduction of the width of all content in all frames.
            \end{itemize}        
        \end{definition}
    \end{minipage}
\end{frame}

\end{document}