Change background color across different environments

Question

I have a long .tex document and I want to change the background color of the parts I have already checked for typos to a light green. I am looking for an easy command that can be used like

\HIGHLIGHT{

<here I want to put a part of my tex file that contains different environments like theorems, figures...>

}

But the \hl{} command cannot contain other environments, the following example does not work:

\documentclass[10pt]{article}         
\usepackage[english]{babel}
\usepackage{amssymb,amsmath,amsthm,amsfonts}
\usepackage{xcolor,soul}

\newtheorem{theorem}{Theorem}
\begin{document}
\section{Introduction}
\hl{
    \begin{theorem}
    A theorem.
    \end{theorem}
}
\end{document}

Do you have any suggestions which command could be used here (the typesetting shall not be changed, only the color)?

Answer 1

As suggested in one of my comments to the question, I would use tcolorbox and its \newtcbtheorem macros, having two basically identical environments, where one uses the checkedstyle and the other one the uncheckedstyle. If a theorem is not checked yet, use \begin{uctheorem}...\end{uctheorem} and edit it later to \begin{theorem}...\end{theorem} or just remove the colback={green!50!white} statement from the definition of uncheckedstyle.

In the very end, a search-and-replace of all uctheorem occurrences by theorem would be the best way, in my point of view, but that is a matter of taste, of course.

Another option is to use a 'real' tcolorbox environment which allows local specification of options, which is not possible with the tcbtheorem environments.

\documentclass[10pt]{article}         
\usepackage[english]{babel}
\usepackage{amssymb,amsmath,amsthm,amsfonts}
\usepackage{xcolor}
\usepackage[most]{tcolorbox}

\tcbset{%
  checkedstyle/.style={breakable,enhanced, sharp corners,colback={yellow!50!white}},
  uncheckedstyle/.style={checkedstyle,colback={green!50!white}}
}

\newtcbtheorem{theorem}{Theorem}{checkedstyle}{theo}

\newtcbtheorem{uctheorem}{Theorem}{uncheckedstyle}{theo}




\begin{document}
\section{Introduction}
\begin{theorem}{My theorem}{foo}
  A theorem.
\end{theorem}

\begin{uctheorem}{My other theorem}{foobar}
  An unchecked theorem
\end{uctheorem}

\end{document}

Answer 2

As an alternative that should work well for your use-case of highlighting arbitrary parts of a LaTeX document, an interesting approach is to partially color the page background using the color and afterpage packages (based on https://tex.stackexchange.com/a/237427/223749). This has the advantage that you do not need to change your content at all and formatting will not be affected. The highlighting will only cover full lines and include the left and right margins as well, but I guess that is not an issue for your use-case. Also, if there are floats inside your highlighting environment and they float out of it, they will not be highlighted.

MWE, including a theorem, a figure and a page break:

\documentclass{article}

\usepackage{mwe}

\usepackage{amssymb,amsmath,amsthm,amsfonts}
\newtheorem{theorem}{Theorem}

\usepackage{color}
\definecolor{lightgreen}{rgb}{0.56, 0.93, 0.56}

\usepackage{afterpage}

\makeatletter
% Macro \changepagecolor has the same syntax as \pagecolor or \color
% with an optional argument and a mandatory argument.
\newcommand*{\changepagecolor}{%
  \@ifnextchar[\@changepagecolor@i\@changepagecolor@ii
}
% Case: \changepagecolor[...]{...}
\def\@changepagecolor@i[#1]#2{%
  \@changepagecolor@do{[{#1}]{#2}}%
}
% Case: \changepagecolor{...}
\newcommand*{\@changepagecolor@ii}[1]{%
  \@changepagecolor@do{{#1}}%
}
\newcommand*{\@changepagecolor@do}[1]{%
  % Fill the remaining space with a colored rule
  \begingroup
    \offinterlineskip
    \hbox to 0pt{%
      \kern-\paperwidth
      \vtop to 0pt{%
        \color#1%
        \hrule width 2\paperwidth height \paperheight
        \vss
      }%
      \hss
    }%
  \endgroup
  % Set page color for the next page
  \afterpage{\pagecolor#1}%
}
\makeatother

\newenvironment{highlight}%
  {\changepagecolor{lightgreen}}%
  {\changepagecolor{white}}


\begin{document}
\blindtext
\blindtext
\blindtext
\blindtext

\begin{highlight}
\blindtext

\begin{theorem}
    a theorem.
\end{theorem}

\begin{figure}[!h]
    \includegraphics[width=.4\textwidth]{example-image-a}\hfill
    \includegraphics[width=.4\textwidth]{example-image-b}
    \caption{This is a figure caption within the custom highlight environment}
\end{figure}
\end{highlight}

\blindtext
    
\end{document}

The result: