\documentclass{beamer}

\input{template_short.tex}

%% use one of the two below
% \colorlet{main}{red!50!black}
% \colorlet{main}{purple}

%-------------------main body-------------------------%

\author{Your Name}
\title{Presentation Title}
\date{January 1, 2018}

\begin{document}

\frame[plain]{\titlepage}

\begin{frame}
\frametitle{Outline}
\tableofcontents
\end{frame}

\section{Page Title}

\begin{frame}
\frametitle{Page Title}

TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems.

\vspace{0.4cm}

unordered list below

\begin{itemize}
\item The first item
\item The second item
\item The third item
\item The fourth item
\end{itemize}

\end{frame}

\section{Display Theorem}

\subsection{first subsection}

\subsection{second subsection}



\begin{frame}
  \frametitle{Display Theorem}
  \begin{theorem}
    $1 + 2 = 3$
  \end{theorem}
  \begin{proof}
    $$1 + 1 = 2$$
    $$1 + 1 + 1 = 3$$
  \end{proof}
\end{frame}

\section{Sample frame title}

\begin{frame}
\frametitle{Sample frame title}
This is a text in second frame.
For the sake of showing an example.

\begin{itemize}
 \item Text visible on slide 1
 \item Text visible on slide 2
 \item Text visible on slide 3
\end{itemize}

\vspace{0.3cm}

another example

\begin{itemize}\itemsep0em
 \item Text visible on slide 1
 \item Text visible on slide 2
 \item Text visible on slide 3
\end{itemize}
\end{frame}

\begin{frame}
  \begin{proof}
    $$
 \frac{1}{\displaystyle 1+
   \frac{1}{\displaystyle 2+
   \frac{1}{\displaystyle 3+x}}} +
 \frac{1}{1+\frac{1}{2+\frac{1}{3+x}}}
$$
$$\int_0^\infty e^{-x^2} dx=\frac{\sqrt{\pi}}{2}$$
\begin{equation} x=y+3 \label{eq:xdef}
\end{equation}
In equation (\ref{eq:xdef}) we saw $\dots$
  \end{proof}
\end{frame}


\end{document}