# Tcolorbox: Outer style doesn't work

I am trying define different styles for nested tcolorboxes as in the following example. However the outer style doesn't seem to apply. Furthermore in my example "Alice" appears in the inner box and not in the outer one. The borderline setting doesn't apply too etc. What did I wrong?

\documentclass{article}

\usepackage{geometry}

\usepackage[most]{tcolorbox}
\definecolor{outer}{named}{blue}
\definecolor{inner}{named}{red}

\newtcolorbox{email}[1]{%
every box/.style={
colback=white,
boxrule=0pt,
coltitle=black,
fontupper=\small\sffamily,
fonttitle=\small\sffamily,
title=\parbox{\linewidth}{#1\par},
},
every box on layer 1/.style={
reset,
every box,
grow to right by=-1ex,
grow to left by=-1ex,
borderline west={3pt}{0pt}{outer!80},
colframe=outer!60,
colbacktitle=outer!15
},
every box on layer 2/.style={
reset,
every box,
grow to right by=0mm,
grow to left by=-1ex,
borderline west={2pt}{0pt}{inner!80},
colframe=inner!60,
colbacktitle=inner!15,
},
}

\usepackage{lipsum}

\begin{document}

\begin{email}{Alice}
\lipsum[1]
\begin{email}{Bob}
\lipsum[2]
\end{email}
\lipsum[3]
\begin{email}{Bob}
\lipsum[4]
\end{email}
\lipsum[5]
\end{email}

\end{document}


Output:

This is not an answer but a long command. I don't know why it happens but if you declare all every box ... into an external tcbset declaration, your settings work. It seems that every box declarations doesn't work inside a \newtcolorbox:

\documentclass{article}

\usepackage{geometry}

\usepackage[most]{tcolorbox}
\definecolor{outer}{named}{blue}
\definecolor{inner}{named}{red}

\tcbset{
every box/.style={
colback=white,
boxrule=0pt,
coltitle=black,
fontupper=\small\sffamily,
fonttitle=\small\sffamily,
},
every box on layer 1/.style={
reset,
every box,
grow to right by=-1ex,
grow to left by=-1ex,
borderline west={3pt}{0pt}{outer!80},
colframe=outer!60,
colbacktitle=outer!15
},
every box on layer 2/.style={
reset,
every box,
grow to right by=0mm,
grow to left by=-1ex,
borderline west={2pt}{0pt}{inner!80},
colframe=inner!60,
colbacktitle=inner!15,
},
}

\newtcolorbox{email}[1]{%
title=\parbox{\linewidth}{#1\par},
}

\usepackage{lipsum}

\begin{document}

\begin{email}{Alice}
\lipsum[1]
\begin{email}{Bob}
\lipsum[2]
\end{email}
\lipsum[3]
\begin{email}{Bob}
\lipsum[4]
\end{email}
\lipsum[5]
\end{email}

\end{document}