%%
%% The LaTeX Companion, 3ed
%%
%% Example 8-4-27 on page I-629 in "Raster applications".
%%
%% 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}

%StartShownPreambleCommands
\usepackage{tcolorbox}
\tcbuselibrary{skins,raster}
%StopShownPreambleCommands

\begin{document}
\begin{tcbraster}[raster columns=2,
  raster equal height,
  raster every box/.style=
    {size=small,valign=center,halign=center,
     colframe=blue!50,colback=blue!10,
     title=\Alph{tcbrasternum}
           (\thetcbrasterrow/\thetcbrastercolumn)}]
 \begin{tcolorbox}One, one, 1, \ldots\end{tcolorbox}
 \begin{tcolorbox}Two\end{tcolorbox}
 \begin{tcboxedraster}[raster columns=1]{blankest}
   \begin{tcolorbox}Three\end{tcolorbox}
   \begin{tcolorbox}Four\end{tcolorbox}
   \begin{tcolorbox}Five\end{tcolorbox}
 \end{tcboxedraster}
 \begin{tcolorbox}Six\end{tcolorbox}
\end{tcbraster}
\end{document}
