%%
%% The LaTeX Companion, 3ed
%%
%% Example 4-1-40 on page I-286 in "thmtools --- Advanced theorem declarations".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See
https://www.latex-project.org/lppl.txt for details.
%%
\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{135.0pt}
\usepackage{microtype} % for better spacing
\addtolength\textwidth{-10pt}
%StartShownPreambleCommands
\usepackage{amsthm,thmtools,xcolor}
\declaretheorem[style=remark,
shaded={padding=5pt,leftmargin=-10pt,
textwidth=.8\columnwidth}
]{remark}
\declaretheorem[sibling=remark,
shaded={rulecolor=blue,rulewidth=2pt,
bgcolor=white}
]{action}
%StopShownPreambleCommands
\begin{document}
\noindent Text to show the left margin.
\begin{remark}
We number remarks together with actions
but we use a gray background for them.
\end{remark}
\begin{action}[Background]
Background color needs resetting!
\end{action}
\end{document}
