[Tex/LaTex] Beamer Right and Left borders

Question

I want to show a thick line on the left and right borders, i found the similar quetion here Right border but just for right border, here is my MWE:

\documentclass{beamer}
\usetheme[secheader]{Madrid}
\author{diabonas}
\title{Frame border}
\setbeamertemplate{background canvas}{%
{\color{black}\hspace*{\dimexpr\paperwidth-3pt\relax}\rule{10pt}{\paperheight}}%    
}
\begin{document}
\begin{frame}
content
\end{frame}
\frame{Content}
\begin{frame}
content
\end{frame}
\end{document}

I want slides to look like this

Answer 1

TYou set the background to be first a space of length \paperwidth-3pt and then a bar of 10pt (of which only 3pt is visible). If you start with a bar of 3pt, then a space of length \paperwidth-6pt and the ending bar, it should be what you want.

\documentclass{beamer}
\usetheme[secheader]{Madrid}
\author{diabonas}
\title{Frame border}
\setbeamertemplate{background canvas}{%
{\color{black}\rule{3pt}{\paperheight}\hspace*{\dimexpr\paperwidth-6pt\relax}\rule{10pt}{\paperheight}}%    
}
\begin{document}
\begin{frame}
content
\end{frame}
\frame{Content}
\begin{frame}
content
\end{frame}
\end{document}