Anordnungen verschachtelter tcolorbox.

\documentclass{article}
\renewcommand{\familydefault}{\sfdefault}

\usepackage{varwidth}
 \usepackage{array}
 \usepackage{colortbl}
 \usepackage{amsmath}
\usepackage{sfmath}
\usepackage{lipsum}

\usepackage{tikz}
\usetikzlibrary{positioning}
 \usetikzlibrary{calc}
 \usetikzlibrary{shadings}
\usetikzlibrary{shapes.geometric, angles,quotes,babel,3d}

\usepackage[most]{tcolorbox}
 \tcbuselibrary{skins,xparse}
 \tcbuselibrary{breakable}
\tcbset{
innenboxstyle/.style={
% Horizontale Aufteilung ===========
%sidebyside adapt=right, % nein, sondern
% lefthand width=4cm, % entweder absolutes Maß
lefthand ratio=0.65, % oder Verhältnis festlegen
% Farben und Schrift ===========
%lower separated=false,% kein Effekt, da eh weg
bicolor,colback=gray!10, colbacklower=white,
fonttitle=\bfseries, sharpish corners, colframe=gray!20!black, colbacktitle=gray!40,coltitle=black,
scale=1.0, % besser die tikzpictures skalieren, statt die ganzen Boxen
% Alignment  ===========
sidebyside align=top seam, % vermutlich gewünscht
left=0mm, % Sonst Probleme mit dem halign lower, 
% der boxsep noch gibt einen zusätzlichen Defalult-Abstand
valign lower=center, 
halign lower=center, 
},
seitenboxstyle/.style={
sidebyside, 
sidebyside align=top seam, 
sidebyside gap=3mm,
sharpish corners,
lower separated=false,
colframe=gray!10!black,colback=white,fonttitle=\bfseries,
%height fill,
% grundsätzlich seiten-hoch % evtl. brauchbar
},
}


\begin{document}

\tcbset{colframe=gray!10!black,colback=white,fonttitle=\bfseries}
\begin{tcolorbox}[title=I. Körperberechnung,sharpish corners]
\tcbsidebyside[title=Quadratische Pyramide,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=\frac{1}{3}\cdot a^{2}\cdot h
\end{equation*}
}{%
\pgfmathsetmacro{\a}{3.5}%  
\pgfmathsetmacro{\b}{3.5}%  
\pgfmathsetmacro{\h}{4}%
\begin{tikzpicture}[scale=0.7,
font=\footnotesize, 
z ={(0,0,-cos(45))},
]

\coordinate[] (A) at (0,0,0); 
\coordinate[label=right:] (B) at (\a,0,0); 
\coordinate[label=right:] (C) at (\a,0,\b); 
\coordinate[label=below:] (D) at (0,0,\b); 
\coordinate[label=below:] (MBC) at (\a,0,0.5*\b);
\coordinate[] (M) at (0.5*\a,0,0.5*\b); 
\path[] (M) --+ (0,\h,0) coordinate[label=\textsf{S}] (S);

% Grundfläche
\fill[lightgray] (A) -- (B) -- (C) -- (D) --cycle;
\draw[] (A) -- (B) node[midway, below]{\textsf{a}} -- (C) node[pos=0.6, below]{}; 
\draw[densely dashed] (A) -- (D) -- (C); 
% Höhe
\draw[] ($(M)!-5pt!(C)$) -- ($(M)!5pt!(C)$) ; 
\draw[] ($(M)!-5pt!(B)$) -- ($(M)!5pt!(B)$) ; 
\draw[] (M) -- (S) node[midway, right]{\textsf{h}}; 
\draw[] (S) -- (MBC) node[midway, right]{$\textsf{h}_{\textsf{a}}$}; 
% Mantellinien
\draw[densely dashed] (D) -- (S); 
\foreach \P in {A,B,C}{  \draw[] (\P) -- (S);     }

%\begin{scope}[-latex, shift={(0,\h-0.3,0)}]
%\foreach \P/\s/\Pos in {(1,0,0)/x/below, (0,1,0)/y/left, (0,0,2)/z/right} 
%\draw[] (0,0,0) -- \P node[\Pos, pos=0.9,inner sep=2pt]{$\s$};
%\end{scope}
\end{tikzpicture}
}
\tcbsidebyside[title=Kugel,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}
{%
    \begin{tikzpicture}
  \shade[ball color = gray!40, opacity = 0.4] (0,0) circle (1.5cm);
  \draw (0,0) circle (1.5cm);
  \draw (-1.5,0) arc (180:360:1.5 and 0.6);
  \draw[dashed] (1.5,0) arc (0:180:1.5 and 0.6);
  \fill[fill=black] (0,0) circle (1pt);
  \draw[dashed] (0,0 ) -- node[above]{\textsf{r}} (1.5,0);
\end{tikzpicture}
}
\tcbsidebyside[title=Kegel,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}{%
\pgfmathsetmacro{\a}{4}%  
\pgfmathsetmacro{\b}{5}%  
\pgfmathsetmacro{\h}{3}%
\begin{tikzpicture}
\fill[
  top color=gray!50,
  bottom color=gray!10,
  shading=axis,
  opacity=0.25
  ] 
  (0,0) circle (1.5cm and 0.5cm);

  (1.5,0) -- (0,4) -- (-1.5,0) arc (180:360:1.5cm and 0.5cm);
\draw 
  (-1.5,0) arc (180:360:1.5cm and 0.5cm) -- (0,4) -- cycle;
\draw[dashed]
  (-1.5,0) arc (180:0:1.5cm and 0.5cm);
\draw[dashed]
  (1.5,0) -- node[below] {$r$} (0,0) -- node[left] {h} (0,4) ;
%\draw 
  %(0,8pt) -- ++(8pt,0) -- (8pt,0);   
\end{tikzpicture}
}
\tcblower
\tcbsidebyside[title=Zylinder,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}
{%
\begin{tikzpicture}
\fill[top color=gray!50!black,bottom color=gray!10,middle color=gray,shading=axis,opacity=0.25] (0,0) circle (1.5cm and 0.5cm);
(1.5,0) -- (1.5,4) arc (360:180:1.5cm and 0.5cm) -- (-1.5,0) arc (180:360:1.5cm and 0.5cm);
\fill[top color=gray!90!,bottom color=gray!2,middle color=gray!30,shading=axis,opacity=0.25] (0,4) circle (1.5cm and 0.5cm);
\draw (-1.5,4) -- (-1.5,0) arc (180:360:1.5cm and 0.5cm) -- (1.5,4) ++ (-1.5,0) circle (1.5cm and 0.5cm);
\draw[densely dashed] (-1.5,0) arc (180:0:1.5cm and 0.5cm);
\draw[dashed]
  (1.5,0) -- node[below] {$r$} (0,0) -- node[left] {h} (0,4) ;
\end{tikzpicture}
}

\tcbsidebyside[title=Quader,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}
{%
\begin{tikzpicture}[%
x={(1cm,0cm)},
y={(0cm,1cm)},
z={({0.5*cos(45)},{0.5*sin(45)})},
]
  \def\a{2}
  \def\b{3}
  \def\c{4}

\coordinate (A) at (0,0,0); 
\coordinate (B) at (\a,0,0) ;
\coordinate (C) at (\a,\b,0); 
\coordinate (D) at (0,\b,0); 
\coordinate (E) at (0,0,\c); 
\coordinate (F) at (\a,0,\c); 
\coordinate (G) at (\a,\b,\c); 
\coordinate (H) at (0,\b,\c);

%Ecken
\node[left= 1pt of A]{};
\node[right= 1pt of B]{};
\node[right= 1pt of C]{};
\node[left= 1pt of D]{};
\node[left= 1pt of E]{};
\node[right= 1pt of F]{};
\node[right= 1pt of G]{};
\node[left= 1pt of H]{};

%Kanten
\draw[] (A) 
-- (B)  node[midway, below]{\small a}
-- (C)      node[midway, right]{\small c}
-- (D)  
-- (A)  ;
\draw[] (B)
 -- (F) node[midway, right]{\small b}
  -- (G) -- (C);
\draw[] (G) -- (H) -- (D);
\draw[densely dashed] (A) -- (E) -- (F);
\draw[densely dashed] (E) -- (H);
\fill[top color=gray!50!black,bottom color=gray!10,middle color=gray,shading=axis,opacity=0.25](A)--(B)--(F)--(E);
\fill[top color=gray!50!black,bottom color=gray!10,middle color=gray,shading=axis,opacity=0.25](D)--(C)--(G)--(H);
\end{tikzpicture}
}
\tcbsidebyside[title=Allgemeine Prismen,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}
{%
\tikzset{
  xyz/.style={x={(-.385cm,-.385cm)},y={(1cm,0cm)},z={(0cm,1cm)}},
  flaeche/.style={fill=gray!10,opacity=.5},
}
\begin{tikzpicture}[xyz]% z-Achse zeigt nach oben
% Koordinaten in zwei zur xy-Ebene parallelen Ebenen definieren
  \foreach[count=\i] \z in {0,4}
    \path
        (0,1,\z)coordinate(A\i)
        (0,4,\z)coordinate(B\i)
        (-2,2,\z)coordinate(C\i)
        (-2,1,\z)coordinate(D\i)
    ;
% Grund- und Deckfläche füllen, gegebenenfalls doppelt
  \foreach \i in {1,2,2}
    \path[flaeche](A\i)--(B\i)--(C\i)--(D\i)--cycle;
% Seitenfläche(n) füllen
 % \foreach \i/\j in {A/B}
   % \path[flaeche](\i1)--(\i2)--(\j2)--(\j1)--cycle;
% sichtbare Kanten zeichnen
  \path[draw](A2)--(B2)--(C2)--(D2)--(A2)--(A1)--(B1)--(B2);
% verdeckte Kanten zeichnen
  \path[draw,dashed](A1)--(D1)--(C1)--(B1) (C1)--(C2) (D1)--(D2);
\end{tikzpicture}
}
\end{tcolorbox}
%----------------------------------------------------------------------------------------------
%----------------------------------------------------------------------------------------------
%----------------------------------------------------------------------------------------------
\tcbset{colframe=gray!10!black,colback=white,fonttitle=\bfseries}
\begin{tcolorbox}[title=II. Flächenberechnung,sharpish corners]
\tcbsidebyside[title=Quadrat,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Flächeninhalt}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Umfang}
\begin{equation*}
O=x+z
\end{equation*}
}{%
\begin{tikzpicture}[scale=0.5
]
\def\a{4}

\coordinate (A) at (0,0); 
\coordinate (B) at (\a,0) ;
\coordinate (C) at (0,\a); 
\coordinate (D) at (\a,\a); 
\draw[very thick] (A) -- (B) -- (D) -- (C) -- cycle;
\path (A) -- node [midway,below] {a} (B);
\end{tikzpicture}
}
\tcbsidebyside[title=Rechteck,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}
{%
\begin{tikzpicture}[scale=0.5,very thick
]
\def\a{5}
\def\b{2}

\coordinate (A) at (0,0); 
\coordinate (B) at (\a,0) ;
\coordinate (C) at (0,\b); 
\coordinate (D) at (\a,\b); 
\draw[very thick] (A) -- (B) -- (D) -- (C) -- cycle;
\path (A) -- node [midway,below] {a} (B);
\path (B) -- node [midway,right] {b} (D);
\end{tikzpicture}
}
\tcbsidebyside[title=Trapez,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}{%
\begin{tikzpicture}[my angle/.style={font=\small, draw, angle eccentricity=1.75, angle radius=3mm},very thick]
  \node (a) [trapezium, trapezium angle=60, minimum width=50mm, draw, very thick, label=above:b, label=below:a, label=right:c, label=left:d] {};
  \draw [densely dashed] (a.north west) coordinate (a nw) -- (a nw |- a.south) node [midway,right] {$h$} ;
 % \draw (a nw |- a.south) ++(0,1.5mm) -| ++(-1.5mm,-1.5mm) (a ne |- a.south) +%+(0,1.5mm) -| ++(1.5mm,-1.5mm);
  \coordinate (a blc) at (a.bottom left corner);
  \coordinate (a brc) at (a.bottom right corner);
  %\pic [my angle, "$\alpha$"] {angle=a1--a blc--a nw};
  %\pic [my angle, "$\alpha$"] {angle=a ne--a brc--a1};
  %\pic [my angle, "$\beta$"] {angle=a blc--a nw--a1};
  %\pic [my angle, "$\beta$"] {angle=a2--a ne--a brc};
\end{tikzpicture}
}
\tcbsidebyside[title=Parallelogramm,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}
{%
\begin{tikzpicture}[my angle/.style={font=\small, draw, angle eccentricity=1.75, angle radius=3mm}]
  \node (a) [trapezium,trapezium left angle=60, trapezium right angle=120, minimum width=50mm, draw, very thick, label=below:a, label=left:b] {};
  \draw [densely dashed, very thick] (a.north west) coordinate (a nw) -- (a nw |- a.south) node [midway,right] {$h$} ;
 % \draw (a nw |- a.south) ++(0,1.5mm) -| ++(-1.5mm,-1.5mm) (a ne |- a.south) +%+(0,1.5mm) -| ++(1.5mm,-1.5mm);
  \coordinate (a blc) at (a.bottom left corner);
  \coordinate (a brc) at (a.bottom right corner);
  %\pic [my angle, "$\alpha$"] {angle=a1--a blc--a nw};
  %\pic [my angle, "$\alpha$"] {angle=a ne--a brc--a1};
  %\pic [my angle, "$\beta$"] {angle=a blc--a nw--a1};
  %\pic [my angle, "$\beta$"] {angle=a2--a ne--a brc};
\end{tikzpicture}
}

\tcbsidebyside[title=Rechtwinkliges Dreieck,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}
{%
\begin{tikzpicture} [very thick]
\draw (-2,0)coordinate[](A)
    --(2,0)coordinate[](B)
    --(-2,2)coordinate[](C)
    --cycle;
% rechte Winkel
    \pic[draw,fill=gray!10,fill opacity=0.5,angle radius=4mm,"$\pmb{\cdot}$" opacity=1]
      {angle=B--A--C};
% Streckenbezeichnungen
\path (A) -- node [midway,below] {b} (B);
\path (A) -- node [midway,left] {a} (C);
\path (B) -- node [midway,above] {c} (C);
\end{tikzpicture} 
}
\tcbsidebyside[title=Kreis,
sidebyside adapt=right,
bicolor,colback=gray!10,colbacklower=white,
fonttitle=\bfseries,sharpish corners,colframe=gray!20!black,colbacktitle=gray!40,coltitle=black,scale=0.5
]{%
\subsubsection*{Mantel}
\begin{equation*}
M=x+y
\end{equation*}
\subsubsection*{Oberfläche}
\begin{equation*}
O=x+z
\end{equation*}
\subsubsection*{Volumen}
\begin{equation*}
V=x^{3}
\end{equation*}
}
{%
\begin{tikzpicture}
\def\a{2}
\def\r{1.8}
\coordinate (A) at (0,0); 
\coordinate (B) at (\r,0) ;
\coordinate (C) at (0,\r) ;
\coordinate (D) at (0,-\r) ;

\filldraw[ fill=white, very thick](A) circle (\r);
\draw[color=black] (A) node {$\pmb{+}$};
%\draw[color=black] (A) node[below] {M};
\draw[color=black,dotted,very thick] (A)-- (B) node[midway,below]{r};
\draw[color=gray,very thick] (C)-- (D) node[midway,left,color=black]{d};
\end{tikzpicture}
}
\end{tcolorbox}
\end{document}