%%
%% The LaTeX Companion, 3ed
%%
%% Example 8-4-20 on page I-624 in "Adding overlays, watermarks, and other backgrounds".
%%
%% 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{123.0pt}

%StartShownPreambleCommands
\usepackage[skins]{tcolorbox}
%StopShownPreambleCommands

\begin{document}
\begin{tcolorbox}[enhanced,title=Text as a watermark,
                  watermark text=\textbf{Example},
                  watermark color=blue,watermark opacity=0.1,
                  watermark stretch=0.95]
  This shows a box with the text in the background.
  Make it light so that main text remains readable!
\end{tcolorbox}
\end{document}