\documentclass[12pt,a4paper]{article}

\usepackage[a4paper,text={16.5cm,25.2cm},centering]{geometry}
\usepackage{lmodern}
\usepackage{amssymb,amsmath}
\usepackage{ifxetex}
\ifxetex
  \usepackage{mathspec}
\fi
\usepackage{graphics}
\usepackage{microtype}
\usepackage{hyperref}
\setlength{\parindent}{0pt}
\setlength{\parskip}{1.2ex}

\hypersetup
       {   pdfauthor = { {{{:author}}} },
           pdftitle={ {{{:title}}} },
           colorlinks=TRUE,
           linkcolor=black,
           citecolor=blue,
           urlcolor=blue
       }


{{#:title}}
\title{ {{{ :title }}} }
{{/:title}}

{{#:author}}
\author{ {{{ :author }}} }
{{/:author}}

{{#:date}}
\date{ {{{ :date }}} }
{{/:date}}

{{{ :highlight }}}

\begin{document}

{{#:title}}\maketitle{{/:title}}

{{{ :body }}}

\end{document}

\documentclass[12pt,a4paper]{article}

\usepackage[a4paper,text={16.5cm,25.2cm},centering]{geometry}
\usepackage{lmodern}
\usepackage{amssymb,amsmath}
\usepackage{graphics}
\usepackage{microtype}
\usepackage{hyperref}
\setlength{\parindent}{0pt}
\setlength{\parskip}{1.2ex}

\usepackage{ifxetex,ifluatex}
\newif\ifxetexorluatex
\ifxetex
  \xetexorluatextrue
\else
  \ifluatex
    \xetexorluatextrue
  \else
    \xetexorluatexfalse
  \fi
\fi

\hypersetup
       {   pdfauthor = { {{{:author}}} },
           pdftitle={ {{{:title}}} },
           colorlinks=TRUE,
           linkcolor=black,
           citecolor=blue,
           urlcolor=blue
       }


{{#:title}}
\title{ {{{ :title }}} }
{{/:title}}

{{#:author}}
\author{ {{{ :author }}} }
{{/:author}}

{{#:date}}
\date{ {{{ :date }}} }
{{/:date}}

{{{ :highlight }}}

\ifxetexorluatex
  \usepackage{fontspec}
  \setmainfont{CMU Serif Roman}
  \setmonofont{CMU Typewriter Text}
  \usepackage{unicode-math}
  \setmathfont{Latin Modern Math}
\fi

\begin{document}

{{#:title}}\maketitle{{/:title}}

{{{ :body }}}

\end{document}

Add unicode symbol support based on CMU fonts
Add unicode symbol support based on CMU fonts
