%%
%% The LaTeX Companion, 3ed
%%
%% Example 4-1-41 on page I-287 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{159.0pt}

  \usepackage{microtype}

%StartShownPreambleCommands
\usepackage{amsthm,thmtools}
\declaretheorem[thmbox={L,leftmargin=4.6pt}]{theorem}
\declaretheorem[thmbox={M,nounderline}]{lemma}
\declaretheorem[thmbox={S,bodystyle=\normalfont
                            \small\noindent}]{remark}
%StopShownPreambleCommands

\begin{document}
\begin{theorem}[Style L + left shift]
  There are no typographical challenges.\end{theorem}
\begin{lemma}[Style M + no underline]
  All major application areas are discussed in
  the \LaTeX{} Companion.                 \end{lemma}
\begin{remark}[Style S + font settings]
  Unfortunately this means the book has a large
  number of pages.                       \end{remark}
\end{document}