I would do such stuff by using a tcbraster
or tcbitemize
inside an outer tcolorbox
. The following code example creates colored stripes in blue and red, but every stripe could be given an individual color:
\documentclass{article}
\usepackage[many]{tcolorbox}%
\usepackage{lipsum,geometry}
\begin{document}
\begin{tcolorbox}[enhanced,
boxsep=0pt,top=0pt,bottom=0pt,leftupper=0pt,rightupper=0pt,
toptitle=1mm,bottomtitle=1mm,lefttitle=5mm,righttitle=5mm,
colbacktitle=yellow!20,coltitle=black,title=Box with interior raster,
colback=blue!10,clip upper]
\begin{tcbitemize}[raster columns=1,raster equal skip=0pt,
sharp corners,boxrule=0pt,
raster odd row/.style={empty},
raster even row/.style={tile,colback=red!10}]
\tcbitem
\lipsum[1]
\tcbitem
\lipsum[2]
\tcbitem
\lipsum[1]
\tcbitem
\lipsum[1]
\end{tcbitemize}
\end{tcolorbox}
\clearpage
The same with a new environment:
\newenvironment{mybox}{%
\begin{tcolorbox}[enhanced,
boxsep=0pt,top=0pt,bottom=0pt,leftupper=0pt,rightupper=0pt,
toptitle=1mm,bottomtitle=1mm,lefttitle=5mm,righttitle=5mm,
colbacktitle=yellow!20,coltitle=black,title=Box with interior raster,
colback=blue!10,clip upper]%
\begin{tcbitemize}[raster columns=1,raster equal skip=0pt,
sharp corners,boxrule=0pt,
raster odd row/.style={empty},
raster even row/.style={tile,colback=red!10}]%
}{\end{tcbitemize}\end{tcolorbox}}
\begin{mybox}
\tcbitem
\lipsum[1]
\tcbitem
\lipsum[2]
\tcbitem
\lipsum[1]
\tcbitem
\lipsum[1]
\end{mybox}
\end{document}

\tcbline
does not create 'functional' sub boxes, as\tcblower
would do