%%
%% The LaTeX Companion, 3ed
%%
%% Example 8-4-5 on page I-617 in "Text alignment".
%%
%% 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{231.0pt}

%StartShownPreambleCommands
\usepackage{kantlipsum,tcolorbox}
\tcbset{top=0pt,middle=1mm,bottom=0pt}
%StopShownPreambleCommands

\begin{document}
\scriptsize
\begin{tcolorbox}[halign=right]
   top part \tcblower bottom part
\end{tcolorbox}
\begin{tcolorbox}[parbox=false,
     halign title=center,
     halign lower=right,title=My title]
 \kant[1][2] \par \kant[2][1]
 \tcblower
 \kant[3][1] \par \kant[6][1]
\end{tcolorbox}
\end{document}