I would like to draw something like this with Tikz (exemple given with 4 boxes but it could have more boxes):
For the moment, I have obtained this (thanks to this answer and this one (for the pgfonlayer):
With this code:
\documentclass[tikz, border=2mm]{standalone}
\usetikzlibrary{backgrounds,
fit,
positioning,
shapes.multipart}
\pgfdeclarelayer{layer1}
\pgfdeclarelayer{layer2}
\pgfdeclarelayer{layer3}
\pgfsetlayers{main,layer1,layer2,layer3}
\definecolor{CoreBlue}{HTML}{5b9bd5}
\definecolor{CoreOrange}{HTML}{ec7d2d}
\begin{document}
\tikzset{
base/.style = {text width=#1, align=center, text=white, outer sep=0pt},
base/.default = 17mm,
CB/.style = {base=#1, fill=CoreBlue},
CO/.style = {base=#1, fill=CoreOrange},
}
\begin{tikzpicture}[]
\begin{pgfonlayer}{layer2}
\node (1a) [CB] {Box 1};
\node (1b) [CO,below=0mm of 1a] {Box 2}; \
\end{pgfonlayer}
\begin{pgfonlayer}{layer1}
\node (1) [CB, fit=(1a) (1b)] {};
\end{pgfonlayer}
\begin{pgfonlayer}{layer3}
\node (1c) [CB,below=0mm of 1b] {Box 3}; \\
\end{pgfonlayer}
\end{tikzpicture}
\end{document}





