\PassOptionsToPackage{unicode=true}{hyperref} % options for packages loaded elsewhere
\PassOptionsToPackage{hyphens}{url}
%
\documentclass[
]{article}
\usepackage{lmodern}
\usepackage{amssymb,amsmath}
\usepackage{ifxetex,ifluatex}
\ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex
  \usepackage[T1]{fontenc}
  \usepackage[utf8]{inputenc}
  \usepackage{textcomp} % provides euro and other symbols
\else % if luatex or xelatex
  \usepackage{unicode-math}
  \defaultfontfeatures{Scale=MatchLowercase}
  \defaultfontfeatures[\rmfamily]{Ligatures=TeX,Scale=1}
\fi
% use upquote if available, for straight quotes in verbatim environments
\IfFileExists{upquote.sty}{\usepackage{upquote}}{}
\IfFileExists{microtype.sty}{% use microtype if available
  \usepackage[]{microtype}
  \UseMicrotypeSet[protrusion]{basicmath} % disable protrusion for tt fonts
}{}
\makeatletter
\@ifundefined{KOMAClassName}{% if non-KOMA class
  \IfFileExists{parskip.sty}{%
    \usepackage{parskip}
  }{% else
    \setlength{\parindent}{0pt}
    \setlength{\parskip}{6pt plus 2pt minus 1pt}}
}{% if KOMA class
  \KOMAoptions{parskip=half}}
\makeatother
\usepackage{xcolor}
\IfFileExists{xurl.sty}{\usepackage{xurl}}{} % add URL line breaks if available
\IfFileExists{bookmark.sty}{\usepackage{bookmark}}{\usepackage{hyperref}}
\hypersetup{
  pdftitle={Track changes in LaTeX and HTML},
  pdfborder={0 0 0},
  breaklinks=true}
\urlstyle{same}  % don't use monospace font for urls
\setlength{\emergencystretch}{3em}  % prevent overfull lines
\providecommand{\tightlist}{%
  \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
\setcounter{secnumdepth}{-2}
% Redefines (sub)paragraphs to behave more like sections
\ifx\paragraph\undefined\else
  \let\oldparagraph\paragraph
  \renewcommand{\paragraph}[1]{\oldparagraph{#1}\mbox{}}
\fi
\ifx\subparagraph\undefined\else
  \let\oldsubparagraph\subparagraph
  \renewcommand{\subparagraph}[1]{\oldsubparagraph{#1}\mbox{}}
\fi

% set default figure placement to htbp
\makeatletter
\def\fps@figure{htbp}
\makeatother

\RequirePackage[debrief]{silence}
\ErrorsOff
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}
\fancyhead[C]{\leftmark}
\usepackage[markup=underlined,authormarkup=none]{changes}
\definecolor{auth1}{HTML}{4477AA}
\definecolor{auth2}{HTML}{117733}
\definecolor{auth3}{HTML}{999933}
\definecolor{auth4}{HTML}{CC6677}
\definecolor{auth5}{HTML}{AA4499}
\definecolor{auth6}{HTML}{332288}
\usepackage[textsize=scriptsize]{todonotes}
\setlength{\marginparwidth}{3cm}
\makeatletter
\setremarkmarkup{\todo[color=Changes@Color#1!20]{\sffamily\textbf{#1:}~#2}}
\makeatother
\newcommand{\note}[2][]{\added[#1,remark={#2}]{}}
\newcommand\hlnotesingle{%
  \bgroup
  \expandafter\def\csname sout\space\endcsname{\bgroup \ULdepth =-.8ex \ULset}%
  \markoverwith{\textcolor{yellow}{\rule[-.5ex]{.1pt}{2.5ex}}}%
  \ULon}
\newcommand\hlnote[1]{\let\helpcmd\hlnotesingle\parhelp#1\par\relax\relax}
\long\def\parhelp#1\par#2\relax{%
  \helpcmd{#1}\ifx\relax#2\else\par\parhelp#2\relax\fi%
}

\makeatletter
\newcommand\ifmoving{%
  \ifx\protect\@unexpandable@protect
      \expandafter\@firstoftwo
  \else
      \expandafter\@secondoftwo
  \fi
}

\newcommand{\gobbletwo}[2][]{\@bsphack\@esphack}
\newcommand{\gobbleone}[1][]{\@bsphack\@esphack}

\let\oldadded\added
\let\olddeleted\deleted
\let\oldhlnote\hlnote
\let\oldnote\note
\renewcommand{\added}{\ifmoving{\gobbleone}{\oldadded}}
\renewcommand{\deleted}{\ifmoving{\gobbletwo}{\olddeleted}}
\renewcommand{\hlnote}{\ifmoving{}{\oldhlnote}}
\renewcommand{\note}{\ifmoving{\gobbletwo}{\oldnote}}
\makeatother
\definechangesauthor[name={FKA}, color=auth1]{FKA}
\definechangesauthor[name={JFK}, color=auth2]{JFK}
\definechangesauthor[name={Jesse Rosenthal}, color=auth3]{JR}
\definechangesauthor[name={MCW}, color=auth4]{MCW}
\definechangesauthor[name={SWS}, color=auth5]{SWS}

\title{Track changes in LaTeX and HTML}
\date{}

\begin{document}
\maketitle

{
\setcounter{tocdepth}{3}
\tableofcontents
}
\hypertarget{track-changes-in-latex-and-html}{%
\section{Track changes in LaTeX and HTML}\label{track-changes-in-latex-and-html}}

A \note[id=MCW]{I agree!}\hlnote{\textbf{simple}} comment from me.

This is a text with \added[id=MCW]{an exciting} insertion.

This is/was a text with a \deleted[id=SWS]{short} deletion.

\added[id=FKA]{Here is the text to be moved.}

\deleted[id=JFK]{Here is the text to be moved.}

Here is a \note[id=JFK]{Why?}\hlnote{com\added[id=SWS]{m}ent with nest\deleted[id=FKA]{t}ed changes}.

Here is a multi-line paragraph containing some text and a long deletion \deleted[id=MCW]{short insertion} wrapping over two lines.

This is \note[id=MCW]{A comment across paragraphs.}\hlnote{a new paragraph.

And so} is this.

One \note[id=JR]{This one has multiple paragraphs. \newline \newline See?}\hlnote{more}.

\hypertarget{a-header-width-a-notecomment}{%
\section{\texorpdfstring{A \emph{header} wi\deleted[id=FKA]{d}th \added[id=JFK]{a} \note[id=FKA]{Note}\hlnote{comment}}{A header with  comment}}\label{a-header-width-a-notecomment}}

Some unmodified text \ldots{}

\newpage

\ldots{} continued from previous page just to test page headers in supporting formats (LaTeX, DOCX, etc.).

\end{document}